This might be intended and not a bug, but I wanted to make a post to make sure. I slept Wrecking Ball as he was doing his Piledriver and he still slammed down and knocked us into the air. I know when he get hacked while doing Piledriver the slam does not work, so it makes me think it might be a bug that sleeping him doesn’t stop it. Here’s a video so you can see if you need it.
Likely latency-related. Probably on your screen you landed the sleep before WB hit the ground, but on WB’s screen he moved out of the way and got the piledrive before getting slept.