When you want to create a square shaped hole in another square part , it happens but when you try to walk in , 4 invisible ramps which you cant select , appears. here’s a picture of what ı mean:
toggle this, it’s less performant but useful if you need precise hitboxes (if it’s outside of the map don’t bother).
edit: I should probably explain all 4.
Box: just a box. nothing special, most performant.
Hull: gets the outermost points and connects them. like wrapping paper. that means it’s not cubed, but if the shape goes inwards or creates a hole, it won’t work.
Default: nice approximation. not as performant as the last two. still has problems sometimes, especially with holes, such as the one you have here – a broken doorway.
PreciseConvexDecomposition: slowest, but fixes almost all of the problems and handles holes pretty well. the solution to your problem.