Basically, this is what happened.
I tried to cast 
ult, but 
used his ult to cancel mine at the exact same time my ult was casted. My shield went through to the allied player, but It stopped my teleport (which is normal). The BUG was that my ult wasn't able to be used again. It showed my ult and I couldn't cast it. Completely broke my r for the rest of the game.
We surrendered not too long after, and for the time being, I could not cast my ult.
zions eyebrows2 votesThis used to happen with Malzahar, not sure if it's the same bug in terms of coding but it sounds like it.
BakugoBestBoy1 votesThere is a bug currently where some times a cancelled skill will not show that it's on cooldown when it really is, but with this bug after the cooldown is over you can cast the ability again. Did the game last long enough for you to try ulting again 1-2 minutes later? (Idk the cd of shen ult).
OPTibbersOP1 votesI agree with this. There are a few champions I've played in the past, where if an ult gets cancelled at just the right time, it still goes on cd while the icon doesn't show it on cd. However, after it is off of cd, you can use it again and it resumes its proper function.
