Hi, this is the same issue as https://forums.oracle.com/ords/apexds/post/error-ora-00904-while-having-faceted-search-with-multiple-f-8820 that was responded to by @carsten-czarski-oracle
I'm at APEX 23.1 on OCI ADB. My report view only references tables in the application schema (plus the apex_applications and apex_application_pages views), and I've given the columns double-quoted uppercase aliases. The report query uses a WITH subquery and +MATERIALIZE hint as Carsten suggested. Each facet's source column is correctly set, and all are varchar2. None of these workarounds remove the problem.
Any assistance much appreciated, regards
John