Hi Lee - Affinity Photo was purchased from the App Store and all updates loaded from the App Store. The combination of 1.8.3 and Mac OS 10.15.4 means I cannot launch AP from the icon in the dock. Have used Time Machine to reinstall 1.8.2, but problem persists. I do not know how to revert to 10.15.3. Now back with 1.8.3.
"Best" solution I have found is to go to App Store/ Categories/ Photo and Video/ Affinity Photo and then to select "Open" from the large display. The programme will eventually launch but it is a slow process. Thereafter all appears to function.
I have sent numerous error reports to Apple and maybe they will discover something. Appreciate your interest and any suggestions will be most welcome.
Best regards Bob Dolby