I’ve had the exact same problem before but I don’t know for sure what made it work again.
It should definitely say “Local Windows Debugger”, that is the problem.
I spent quite some time looking into it and at some point it suddenly worked without changing anything so I don’t know what I did.
I thought I had my startup project set on UE4 instead of the game but it sounds like you double checked that that is not the case.
Are you sure the config is still Development UWP and not Editor or something?
Try regenerating the project files.
In case you find the solution, I’d be interested in knowing what the fix was in case it happens again.