When you log in using enterprise user security and get permissions granted via global roles (LDAP/OUT etc.) and you execute a sql tuning advisor task for a statement of another user you got the ORA-00942 error message even if you’ve been granted the proper permissions.
This is an internal bug and applies to Oracle 12.1. As of Oracle support the bug is fixes starting 12.2.
Apply the patch number 21538203 or grant the “select any table” right directly to the shared user who is used for the enterprise users (which is in my opinion the worst workaround I can imagine!).