This may be the same odd RPG Maker issue one other person reported where the menu key wouldn't work. Holding shift and mashing the key in question fixed it, somehow. I'd try that!
I would also check to see if you might have any other input devices connected that could be sending an up input in the background - a controller with drift, maybe.
Something with updating my Steam controller profile seemed to possibly do the trick! Didn't expect that to do anything, but now I can play and kiss girlfriend to my hearts content <3
