I have the same problem. Here's what I do.
When that epic "Application is not owned" window shows, untick the "go to" checkbox and click ok. Then in the epic run fc, it will show ea with loading (or it will disappear). Close loader if it did not disappear, open fc from ea, it will show the same window on epic. Untick checkbox, click ok, the game should start. If it doesn't keep trying, going back and forth between apps, remember to uncheck the checkbox.
I don't know if that's the exact workaround that always worked (I just tested it now and it did) but I'm able to run the game. Anyway this needs to be fixed.
