Galio Ult Bug

Last night, while doing ranked 5's with my team, we were bringing to life the support. We played with Galio for at least 2-3 games and at least once in each game there was a bug where someone within the ult was not taunted and instead could walk right out of the ult.

For example, one specific instance (sorry no video) Galio ulted into a 5 man catch and the adc, Lucian, even though he was in the middle of the ult, auto attacked and killed another champion and then dashed out of the rest of the ult and walked away uninterrupted. I emphasize that it was a 5 man ult as the bug may be in that the number of champs involved in the ult was part of the issue, but the ult had all other champions taunted on the team, there was no , no and no . This occurred twice in our game and ended up costing us the game, since the Lucian was the primary target and could not be cc'd.

I will try to replicate the issue and grab it on stream in order to show proof, but I wanted to post about the issue and find out if it is an already known issue.