I mained cho a few weeks ago and i noticed this.
it was commonly seen against champions with dashes/leaps, I think it has something to do with how abilities are qued up while in a dash.
A s example of this is if you shoot
with your ult as
, while he's mid air, he'll still land on you and do the full combo despite being stunned.
I think the game might consider them already cast or something, and therefore not affected by silence. Like the animation happening late, which is weird.
Another idea is certain micro channels that are mean to match the casting animation can't be cancelled, so it'll look like they cast the ability after you stun/silence them (which is kinda bs as all channels should be broken by cc)
Oh! An example of this is if a vi q's a Cassiopeia while she's winding up her ult, cass's ult will still cast, but be spun to face the direction that vi moved her to face (if that makes sense)
Both hella annoying.