Panning

All other versions of Cubase Pro pans correctly except 9.5.21. In fact panning does not work at all

Try starting Cubase in Safe Start Mode:
https://www.steinberg.net/nc/en/support/knowledgebase_new/show_details/kb_show/safe-start-mode-resetting-the-cubase-preferences.html

Have you got panning turned off on individual channels?

Same problem over here. Grr