ORA-01031 issue in EBS after database upgrade to 12.1

Hi,

We are still running EBS 11.5.10.2 but upgrading our database from 11.2.0.4 to 12.1. We are getting the error message "SQLERRM: ORA-20001: SQL_PLSQL_ERROR: N, ROUTINE, HR_SIGNON.INITIALIZE_HR_SECURITY, N, ERRNO, -1031, N, REASON, ORA-01031: insufficient privileges" on a number of concurrent requests in EBS after the database was upgraded.

The error can be reproduced by running the code block below, that only contains a simple query against the seeded view po_headers_print. The strange thing is that the the below code block always works the first time it is run, but always gets the the above error message when run the second time and all the attempts thereafter. If I close down the the file containing the below code block  and open it again the story repeats itself, it works fine when run the first time but we encounter the above error on the second run and on all attempts