lol did you miss the yasuo windwall?
nah. yasuo wind wall
just searched it up windwall does not block yasuo ult 4:07 NAUTILUS ULT ISNT BLOCKED https://www.youtube.com/watch?feature=player_embedded&v=AeG6kPPHwq8
Ah I just remembered. The R doesn't go through terrain. So you have an explanation for the first but I don't know about the second one. In the Baron Pit however, he uses it on Riven, not you.
You can't Q out of naut's ult. It hit yasuo's wall (which I find very odd, apparently it's a projectile particle)
I'm not sure what's happening. does seem like a bug.