Right, I remember now lol
There is a wall exclusive to the past just to the right, and it seems the rift is just wide enough to catch a sliver of it. Should've made it way smaller just in case instead of matching the tile size, didn't get as much testing since it's the only place in the game where it comes into play from another wall boundary.
Thanks so much for playing and for the report! And if you'd like to give it another shot, you were already a good way through and there's a Reset option in the menu (P for the web build).