I had a related problem a few days ago. It may be related to the installation.

Try this:

1. run catalog.sql in $ORACLE_HOME/rdbms/admin
2. run dbmsstdx.sql in $ORACLE_HOME/rdbms/admin
3. run catproc.sql in $ORACLE_HOME/rdbms/admin

I found that running only catalog and catproc did not successfully create and compile the DBMS_STANDARD package.

You can view DBA_OBJECTS with owner='SYS' and object_type = 'PACKAGE' to see if the packages are valid.

Good luck