Oracle cat index throws invalid sql name exception

Question

We recently upgraded our database to Oracle 12c, and since then it has thrown an exception ORA-44003: invalid sql name when pasted into a table with index cat.

We only have the cat index in one column, which works great with Oracle 11g.

The interesting part: I can insert the same record if I continue. Sometimes in the second, sometimes in the tenth attempt.

Here is the exception:

 Internal Exception: java.sql.SQLException: ORA-44003: invalid SQL name ORA-06512: at "SYS.DBMS_ASSERT", line 479 ORA-06512: at "CTXSYS.DRVDML", line 415 ORA-06512: at "EMISDB.DR$IDX_AML_NOTICE_DESCTC", line 1 ORA-04088: error during execution of trigger 'SONARDB.DR$IDX_NOTICE_DESCTC' 

I reset and created a cat index using a script:

 create index IDX_NOTICE_DESC on NOTICE (DESCRIPTION) indextype is ctxsys.ctxcat 

I would appreciate any advice.