Kevin, FWIW - I did a generic search which resulted in some additional ideas for you to consider:
after closing program the window frame remains
Noting I’m still on Win 10 and haven’t tried installing the RM update yet: Probably unrelated, but 2 other ideas to test, 1) Windows, System, Personalization, Lock screen, turn off Get fun facts, tips, etc.,; and 2) turn off Show lock screen background picture on the sign-in screen.