Alright, now large resolutions are the only ones that work. Both 1920x1080, and 5120x2880 technically work, although the UI is a complete mess on the latter and barely usable on the former. 1600x900 works but anything less, even 1504x846, doesn't. 1280x720 is still stuck in the upper left corner. I even switched my monitor to 1280x720 and it still ran at exactly the same size. 1152x648 (The smallest preset) doesn't work either.
EDIT: 1600x1200 and 800x600 both work, but 1200x900 doesn't.