Update 388 immediately broke all previous projects inherently, even almost blank ones. [SOLVED]

After downloading update 388 I can't run any project made before 388. all previews of anything made before 388 don't even get to the loading screen, they just stay black.

UPDATE: After some testing I found that any project trying to use the loading bar on the loading screen fails to load after 388 update.

Yeah I have the same problem with the previews. It's happening now on an example with a loading bar. (Physics Vehicle)