Collision does not work in some corners of connected walls.

[frostyfan109]

Connected walls (at any angles) may lack true connection at their connecting corner due to lack of ray precision. This somehow allows for the collision detection to miss it if an object tries to pass at that point.

[frostyfan109]

I've only observed this to occur with protruding corners. This likely also happens with inner corners, but is simply more difficult to pull off.