I can no longer save edits using the Luminar Flex extension in Photos on my Mac after being updated to Catalina 10.15. I see the following message Tried rebooting, but no change. Still can't save...
For other Mac users, here's the official statement from Skylum. In short, if you're a Catalina user you'll be out of luck unless you're running the current versions. In the official statement they give the same workaround that the users posted earlier in the above linked thread.
Which Skylum apps are going to be compatible with macOS Catalina? Luminar 4, Luminar 3, Luminar Flex and Aurora HDR 2019.