expdp full export not exporting all schemas
This is expected behaviour.

FULL


  A full export does not, by default, export system schemas that contain
  Oracle-managed data and metadata. Examples of system schemas that are
  not exported by default include SYS, ORDSYS, and MDSYS.


12.1.0.1 EXPDP Does Not Export APEX Schema (Doc ID 1912162.1)


  This is the expected behavior in 12.1.0.X version, 
  
  This was added, in part, to avoid problem with common objects in a 
  multi-tenant DB, but certainly has been very helpful in eliminating
  errors  report - particularly in full import.  The bit is called
  'ORACLE_MAINTAINED' in [user,all,dba]_objects  dictionary views. Seems
  pretty reasonable that Oracle maintained objects are  not be moved
  around by datapump.