Can you describe the bug a little more? I tried walking through the wall and wasn't able to.
Thanks for the information. I'm still not able to reproduce the bug. (I believe that it is happening! It's just hard to replicate these things sometime.) You mentioned that you were standing about three blocks south of the top wall - about where were you standing in the east / west direction?
I've gone ahead and changed Unity's Tilemap collider from "outline" mode to "polygon" mode. This'll get pushed out in the next update (today or tomorrow). I think this will solve the issue, but I'd like to reproduce the bug first so I can prove it. I do appreciate the bug report and the help :)