AWR auto purge not working after 12.1.0.2 db upgrade

The AWR auto purge is not working after upgrading from 11.2.0.3 to 12.1.0.2.  This is a relatively small standalone test database using ASM (also 12.1.0.2).  I upgraded the database to 12.1.0.2 on 24 Nov, and the retention policy shows as 8 days, but I still have old snapshots, even those from 11.2.0.3.  I am running dbms_workload_repository.drop_snapshot_range to remove the old 11.2.0.3 snapshots, but that will still leave more than 8 days of snapshots in the database.  How do I check on the "health" of the 12.1.0.2 AWR auto purge?  I searched Oracle Support and MOSC but have not found anything