I've encountered this problem: https://3909.zendesk.com/hc/en-us/articles/360010887954-Stuck-in-a-room-under-stairs-on-a-flickering-deck-etc-

So steam can get the preview build, are GOG working on getting this? I don't want to have to replay the whole thing.

A post on steam suggested you can glitch back if you reverse into one of the walls for a bit. After a bit of trying this did happen, so my problem is resolved.

Question still stands as to when GOG will get this fix.

EDIT: GOG got the fix pretty quick - thanks guys.