If you're still running into situations where Waller monsters are spawning their walls right on top of your characters, we would really appreciate a list of steps that you took to get this bug to occur or a video that shows when and where this happens. (While we're super thankful for the reports and screenshots you've submitted thus far, we just need some additional details to figure out what's going on.)
The most frequent times it happens to me is in the middle of my vault or at the end of my vault. As I am tumbling away, a wall will appear in front of me and I somehow vault my way inside of the wall making me stuck.
Also, It just happened to me again today in Act 3, the stairs right before Azmodan's room. A single blue succubus placed a wall perpendicular to the stairs I was on as I was running towards it (while strafing) and got me stuck. I couldn't vault out of it or move in any direction either. The wall consumed all my shots as well. =[
I'll be sure to take pictures of it next time!
Edit: I'm not sure how relevant this information is, but I average 70ms while playing.