Hi Marco,
Thanks for your help on this.
I tried compare from a source account with select_catalog_role to a target account with select_catalog_role so both accounts had access to the dba_views and they owned no objects. The compare window did not display any objects when I selected an object owning schema. The objects for the schema are, however, displayed in the object browser when "all users" or the schema is specified. It looks like the compare is not using the dba views even when "Use DBA view if available" option is checked.