Main window does not appear on Windows 10 64 bit Pro, build 19041

[Kuiriel]

I used to be able to use this without issue on Windows 10 64 bit.

Now when I launch it I can see the exe in task manager, but the usual app window does not pop up on screen anywhere.

Did I do something stupid somewhere? Has anyone else had this issue? Was it caused by some recent update to Windows?