Just completely stuck on this, any way to fix this?
A common cause of this is if you have a Japanese locale, which causes problems for BYOND.

Also in the Discord we recently helped a user who had trouble because for some reason, his Documents folder was stored on OneDrive when he didn't intend it to be. If the default BYOND documents folder (usually in Documents\BYOND) is mounted in the cloud instead of locally, that causes problems too.
Not the first time of myself having THESE issues, however 99 out of 100 times mere ending the processor of byond via task manager, and merely trying to open the software few times solved the case for me.

As Lummox mentioned tough already, i also had that issue with OneDrive and default BYOND documents folder. So be sure to check that Byond folder is in proper place..and not mounted.

Tough as i said, mostly few times quitting and opening solves the case for me. Wont hurt to try!