Having the same issue. The "quick edit" Affinity 1.7.x extensions all work, but roundtrips edits using the "Edit in Affinity Photo" or "Luminar 3" are broken. Unchecking, the resetting the extensions in the Extension Manager, and/or doing the same in System Preferences > Security & Privacy > Photos section makes no difference.
The issue has already been reported in the Serif Labs (Affinity) forums. It's a shame these rather "obvious" functions don't seem to be given proper attention during the beta testing periods.
There are SO many other issues with Catalina (and Mojave) Photos & iOS 13.1.x compatibility. May take a while to all get sorted out.