Using this team with King Louie with Peter disk my team gets stuck for more than a minute while Violet gets super slow…
That’s not a bug. That’s a feature.
Movement speed affects your ability animations, also.
This is a known “issue” with the way Darkwing’s disk works - one of those things that’s working as intended but is broken in certain situations
The 40% slow can stack, so if you’re against a solo hero who can both shield and become invulnerable (ie. Violet) then she can get uber-slowed and stuck in an untargetable state 
Louie’s slow is just increasing the chance of that happening 
combining the 2 slows means that DW’s doesn’t even need to stack, just need unlucky timing
Maybe it’s as you say but I don’t understand why if there is only one character left, no one moves to hit her. In invasion against the boss only he slows down but the other heroes move and hit without running out of time…
it happens when the slow is applied at the exact moment the hero is using a skill that would make them invulnerable - Violet’s green skill, in this case.
Actually, I think when we’ve seen it before with heroes like Cheshire & Beast PB have applied a fix accordingly - @Loutre can we get a similar fix in for Violet?