diff --git a/synapse/cores/common.py b/synapse/cores/common.py
index 070cd0c4e..3364680f6 100644
--- a/synapse/cores/common.py
+++ b/synapse/cores/common.py
@@ -919,6 +919,10 @@ class Cortex(EventBus, DataModel, Runtime, Configable, s_ingest.IngestApi):
         # do the (possibly very heavy) removal of the tag from all known forms.
         [self.delTufoTag(t, valu) for t in self.getTufosByTag(valu)]
 
+        # Flush the tag caches
+        self._core_tags.clear()
+        self._core_tagforms.clear()
+
     @on('node:form', form='syn:tag')
     def _onFormSynTag(self, mesg):
         valu = mesg[1].get('valu')

Synapse fails to create syn:tag node when applying a previously created but deleted tag
New tags can be applied to nodes without first creating an associated syn:tag node; expected behavior is that the first time you apply a new tag, Synapse automatically creates the syn:tag node in the background.
This is true for never-before-seen tags. However, if a tag and its associated syn:tag node are created, then deleted, and they you try to create / apply that same tag again, Synapse fails to create the syn:tag node.
Example (where syn:tag=hurr.derp was previously created, applied to a test node, removed from the test node, and the syn:tag node deleted):
```
cli> ask inet:fqdn=woot.com [#hurr.derp]
inet:fqdn = woot.com
    #foo.bar (added 2017/06/20 19:59:02.854)
    #hurr.derp (added 2017/08/02 21:07:18.579)
(1 results)

cli> ask syn:tag=hurr.derp
(0 results)
```
diff --git a/synapse/tests/test_cortex.py b/synapse/tests/test_cortex.py
index 4255a95f0..b7fcb9880 100644
--- a/synapse/tests/test_cortex.py
+++ b/synapse/tests/test_cortex.py
@@ -1012,6 +1012,28 @@ class CortexTest(SynTest):
         self.eq(len(core.getTufosByTag('lulz.rofl', form='foo')), 0)
         self.eq(len(core.getTufosByTag('lulz.rofl.zebr', form='foo')), 0)
 
+        # Now we need to retag a node, ensure that the tag is on the node and the syn:tag nodes exist again
+        wait = core.waiter(1, 'node:tag:add')
+        node = core.addTufoTag(hehe, 'lulz.rofl.zebr')
+        wait.wait(timeout=2)
+
+        self.isin('#lulz.rofl.zebr', node[1])
+        self.nn(core.getTufoByProp('syn:tag', 'lulz'))
+        self.nn(core.getTufoByProp('syn:tag', 'lulz.rofl'))
+        self.nn(core.getTufoByProp('syn:tag', 'lulz.rofl.zebr'))
+
+        # Recreate expected results from #320 to ensure
+        # we're also doing the same via storm
+        self.eq(len(core.eval('[inet:fqdn=w00t.com +#some.tag]')), 1)
+        self.eq(len(core.eval('inet:fqdn=w00t.com totags(leaf=0)')), 2)
+        self.eq(len(core.eval('syn:tag=some')), 1)
+        self.eq(len(core.eval('syn:tag=some.tag')), 1)
+        self.eq(len(core.eval('syn:tag=some delnode(force=1)')), 0)
+        self.eq(len(core.eval('inet:fqdn=w00t.com totags(leaf=0)')), 0)
+        self.eq(len(core.eval('inet:fqdn=w00t.com [ +#some.tag ]')), 1)
+        self.eq(len(core.eval('inet:fqdn=w00t.com totags(leaf=0)')), 2)
+        self.eq(len(core.eval('syn:tag=some')), 1)
+        self.eq(len(core.eval('syn:tag=some.tag')), 1)
         core.fini()
 
     def test_cortex_splices(self):

pip install -e .
parse_log_pytest
pytest
pytest
3.6
pytest --no-header -rA --tb=line --color=no -p no:cacheprovider -W ignore::DeprecationWarning
attrs @ file:///opt/conda/conda-bld/attrs_1642510447205/work
certifi==2021.5.30
cffi==1.15.1
cryptography==40.0.2
importlib-metadata @ file:///tmp/build/80754af9/importlib-metadata_1631916693255/work
iniconfig @ file:///home/linux1/recipes/ci/iniconfig_1610983019677/work
lmdb==1.6.2
more-itertools @ file:///tmp/build/80754af9/more-itertools_1637733554872/work
msgpack-python==0.5.6
packaging @ file:///tmp/build/80754af9/packaging_1637314298585/work
pluggy @ file:///tmp/build/80754af9/pluggy_1615976315926/work
py @ file:///opt/conda/conda-bld/py_1644396412707/work
pycparser==2.21
pyOpenSSL==23.2.0
pyparsing @ file:///tmp/build/80754af9/pyparsing_1635766073266/work
pytest==6.2.4
-e git+https://github.com/vertexproject/synapse.git@c4259279399bfbe717448739eda74b1f135c8a1a#egg=synapse
toml @ file:///tmp/build/80754af9/toml_1616166611790/work
tornado==6.1
typing_extensions @ file:///opt/conda/conda-bld/typing_extensions_1647553014482/work
xxhash==3.2.0
zipp @ file:///tmp/build/80754af9/zipp_1633618647012/work

name: synapse
channels:
  - defaults
  - https://repo.anaconda.com/pkgs/main
  - https://repo.anaconda.com/pkgs/r
  - conda-forge
dependencies:
  - _libgcc_mutex=0.1=main
  - _openmp_mutex=5.1=1_gnu
  - attrs=21.4.0=pyhd3eb1b0_0
  - ca-certificates=2025.2.25=h06a4308_0
  - certifi=2021.5.30=py36h06a4308_0
  - importlib-metadata=4.8.1=py36h06a4308_0
  - importlib_metadata=4.8.1=hd3eb1b0_0
  - iniconfig=1.1.1=pyhd3eb1b0_0
  - ld_impl_linux-64=2.40=h12ee557_0
  - libffi=3.3=he6710b0_2
  - libgcc-ng=11.2.0=h1234567_1
  - libgomp=11.2.0=h1234567_1
  - libstdcxx-ng=11.2.0=h1234567_1
  - more-itertools=8.12.0=pyhd3eb1b0_0
  - ncurses=6.4=h6a678d5_0
  - openssl=1.1.1w=h7f8727e_0
  - packaging=21.3=pyhd3eb1b0_0
  - pip=21.2.2=py36h06a4308_0
  - pluggy=0.13.1=py36h06a4308_0
  - py=1.11.0=pyhd3eb1b0_0
  - pyparsing=3.0.4=pyhd3eb1b0_0
  - pytest=6.2.4=py36h06a4308_2
  - python=3.6.13=h12debd9_1
  - readline=8.2=h5eee18b_0
  - setuptools=58.0.4=py36h06a4308_0
  - sqlite=3.45.3=h5eee18b_0
  - tk=8.6.14=h39e8969_0
  - toml=0.10.2=pyhd3eb1b0_0
  - typing_extensions=4.1.1=pyh06a4308_0
  - wheel=0.37.1=pyhd3eb1b0_0
  - xz=5.6.4=h5eee18b_1
  - zipp=3.6.0=pyhd3eb1b0_0
  - zlib=1.2.13=h5eee18b_1
  - pip:
      - cffi==1.15.1
      - cryptography==40.0.2
      - lmdb==1.6.2
      - msgpack-python==0.5.6
      - pycparser==2.21
      - pyopenssl==23.2.0
      - tornado==6.1
      - xxhash==3.2.0
prefix: /opt/conda/envs/synapse

synapse/tests/test_cortex.py::CortexTest::test_cortex_tags
synapse/tests/test_cortex.py::CortexTest::test_cortex_addmodel synapse/tests/test_cortex.py::CortexTest::test_cortex_by_type synapse/tests/test_cortex.py::CortexTest::test_cortex_bytype synapse/tests/test_cortex.py::CortexTest::test_cortex_caching synapse/tests/test_cortex.py::CortexTest::test_cortex_caching_add_tufo synapse/tests/test_cortex.py::CortexTest::test_cortex_caching_atlimit synapse/tests/test_cortex.py::CortexTest::test_cortex_caching_del_tufo synapse/tests/test_cortex.py::CortexTest::test_cortex_caching_disable synapse/tests/test_cortex.py::CortexTest::test_cortex_caching_new synapse/tests/test_cortex.py::CortexTest::test_cortex_caching_oneref synapse/tests/test_cortex.py::CortexTest::test_cortex_caching_set synapse/tests/test_cortex.py::CortexTest::test_cortex_caching_tags synapse/tests/test_cortex.py::CortexTest::test_cortex_caching_under_limit synapse/tests/test_cortex.py::CortexTest::test_cortex_choptag synapse/tests/test_cortex.py::CortexTest::test_cortex_comp synapse/tests/test_cortex.py::CortexTest::test_cortex_dict synapse/tests/test_cortex.py::CortexTest::test_cortex_enforce synapse/tests/test_cortex.py::CortexTest::test_cortex_events synapse/tests/test_cortex.py::CortexTest::test_cortex_fire_set synapse/tests/test_cortex.py::CortexTest::test_cortex_getbytag synapse/tests/test_cortex.py::CortexTest::test_cortex_ingest synapse/tests/test_cortex.py::CortexTest::test_cortex_isnew synapse/tests/test_cortex.py::CortexTest::test_cortex_lift_by_cidr synapse/tests/test_cortex.py::CortexTest::test_cortex_lmdb synapse/tests/test_cortex.py::CortexTest::test_cortex_local synapse/tests/test_cortex.py::CortexTest::test_cortex_minmax synapse/tests/test_cortex.py::CortexTest::test_cortex_minmax_epoch synapse/tests/test_cortex.py::CortexTest::test_cortex_modlrevs synapse/tests/test_cortex.py::CortexTest::test_cortex_modlvers synapse/tests/test_cortex.py::CortexTest::test_cortex_module synapse/tests/test_cortex.py::CortexTest::test_cortex_module_datamodel_migration synapse/tests/test_cortex.py::CortexTest::test_cortex_module_datamodel_migration_persistent synapse/tests/test_cortex.py::CortexTest::test_cortex_norm_fail synapse/tests/test_cortex.py::CortexTest::test_cortex_notguidform synapse/tests/test_cortex.py::CortexTest::test_cortex_ram synapse/tests/test_cortex.py::CortexTest::test_cortex_ramhost synapse/tests/test_cortex.py::CortexTest::test_cortex_ramtyperange synapse/tests/test_cortex.py::CortexTest::test_cortex_reqstor synapse/tests/test_cortex.py::CortexTest::test_cortex_rev0 synapse/tests/test_cortex.py::CortexTest::test_cortex_rev0_lmdb synapse/tests/test_cortex.py::CortexTest::test_cortex_rev0_savefd synapse/tests/test_cortex.py::CortexTest::test_cortex_rev0_savefd_lmdb synapse/tests/test_cortex.py::CortexTest::test_cortex_rev0_savefd_sqlite synapse/tests/test_cortex.py::CortexTest::test_cortex_savefd synapse/tests/test_cortex.py::CortexTest::test_cortex_seed synapse/tests/test_cortex.py::CortexTest::test_cortex_seq synapse/tests/test_cortex.py::CortexTest::test_cortex_splice_propdel synapse/tests/test_cortex.py::CortexTest::test_cortex_splicefd synapse/tests/test_cortex.py::CortexTest::test_cortex_splicepump synapse/tests/test_cortex.py::CortexTest::test_cortex_splices synapse/tests/test_cortex.py::CortexTest::test_cortex_splices_errs synapse/tests/test_cortex.py::CortexTest::test_cortex_sqlite3 synapse/tests/test_cortex.py::CortexTest::test_cortex_stats synapse/tests/test_cortex.py::CortexTest::test_cortex_tag_ival synapse/tests/test_cortex.py::CortexTest::test_cortex_tagform synapse/tests/test_cortex.py::CortexTest::test_cortex_tlib_persistence synapse/tests/test_cortex.py::CortexTest::test_cortex_tufo_by_default synapse/tests/test_cortex.py::CortexTest::test_cortex_tufo_del synapse/tests/test_cortex.py::CortexTest::test_cortex_tufo_list synapse/tests/test_cortex.py::CortexTest::test_cortex_tufo_pop synapse/tests/test_cortex.py::CortexTest::test_cortex_tufo_setprop synapse/tests/test_cortex.py::CortexTest::test_cortex_tufo_setprops synapse/tests/test_cortex.py::CortexTest::test_cortex_tufo_tag synapse/tests/test_cortex.py::CortexTest::test_cortex_xact_deadlock
synapse/cores/common.py
synapse/cores/common.py