That's weird. Definitely shouldn't be any invisible walls so not sure what could cause that. Were you able to duck under any of the boxes? There is 3 in total.
So I just ran into the same issue during my recording once you entered the backroom for the first time. The very last box you have to crouch under, to get the bolt cutters. No matter what, it seems like there is an invisible wall blocking me from crouch walking. I was able to Pass the first 3 with no problem. It's just that the last box was the problem. I reset the game 3 times. I deleted the game and reinstalled it and the Issue still persisted.
I hope this helps and hopefully I'll be able to finish the game.
Thanks DrewTheDude