It's possible to get inside of/sandwiched between terrain and minions/creeps
I'm not sure if it's exclusive to Wukong, but I know this NEVER happened prior to 4.20. The reason that I'm not sure if it's Wukong specific is I've only had it happen on Wukong thus far, but I've also only played Wukong in the jungle so far because I'm trying to make sense of it with my main.
What generally will happen is I'll E(Nimbus Strike) into a camp, it usually happens on Red or Blue buff, and I'll get stuck either inside of them or behind them, sandwiched between them and the wall. All move commands at this point do not allow me to move(the champion doesn't even wiggle like it's stuck and trying to get out, it just doesn't respond), and the only way out is to finish the camp. It also might have something to do with W(Decoy) because that skill pushes Wukong forward a little bit when his clone is dropped.
I've also had this happen when NOT using E or Q on Purple side's outer middle turret. A cannon minion sandwiched me between the dead turret and my champion stopped responding to move commands even though there was an obvious path out. No jiggles like it's trying to escape, just stood there like it was rooted until the cannon died.
I haven't had this happen the 4000+ total matches I've played, and it's happened 6 or 7 times since 4.20 was released, so unless I was just spectacularly lucky over countless hours, this is something new with the collision models or the terrain.
Also, I'd like to use this topic to report a longstanding bug, years old, where Wukong will E onto a target, again usually in the jungle, and if you Q immediately afterwards he'll become uncontrollable for 2-3 autoattacks. The Q animation will go through including the sound effect and little ground splash, but the hit will be canceled and he will target another nearby target at random, do the full Q animation, cancel the damage, rinse repeat a few times.
Wukong's Q will also occasionally register damage after he has stealthed from W, causing him to effectively not stealth in the first place even though W was activated after the Q animation had finished.
Those two Wukong bugs are easily reproducible and have been around for years so it would be great to have that fixed.