Workbench freezes on connecting after Ubuntu 18.04 upgrade
After further investigation I managed to resolve this issue, it seems that after the upgrade my settings must've got screwed up. The connection that wasn't even the one I was attempting to use which was a bit strange.

I went into the paths that mentioned in the log:

11:39:08 [WRN][            grt]: /usr/share/mysql-workbench/modules/data/mysql_rdbms_info.xml:1401: link 'om.mysql.rdbms.mysql.driver.native_sshtun' &lt;object &gt; key=owner could not be resolved
11:39:08 [WRN][            grt]: /home/&lt;REPLACED USERNAME&gt;/.mysql/workbench/connections.xml:27: link '6d8ecd74-acad-11e8-9c35-408d5cdbf11f' &lt;object GrtObject&gt; key=owner could not be resolved


And deleted the 'value' tags as well as the connection that was throwing the error and restarted mysql workbench. After the restart some of the connections I had setup were gone (which I can just recreate) but it seems that I can connect fine now.