So that would mean that by round 24, somehow your OB has either too much health relative to Maneater, or not enough - the CB won't hit an unkillable toon with virtually no life, which is why Pain Keeper's heal right before the stun is so important. 

And that's also why it's important that Pain Keeper has the second highest health on the team - to make sure that after her heal, the stun target has some health, enough to get hit, but a lower percentage of his total health than any other toon, so he looks like the best target. So what's your PK's health? And just to be sure, we're talking about a run on void CB, right? 

yeah i know - and PK heals just before CB goes; just as planned. Somehow CB targets ME instead - based on your answer i might need to lower maneaters HP a bit so he will get more healing-percentage; is that understood correctly ?

BTW: health is following:

ME: 35k 2800 def

PK: 38500 / 2200

OB: 44 000 / 1400

ME gets target, guess last 2 guys are irellevant :D - btw ty for answer @L9753 

That looks like it should work fine, it's very similar to mine... don't think ME's HP needs to be reduced then. 

Very strange! Has this happened repeatedly, or just once? A video might help if it happens repeatedly, just to see if there's any visible reason why the CB would change targets at that specific point... 

happened every time when i play nm (and even against magic afinity allthough OB is weak affinity). When playing nm i raise OB speed to 121 and its all in sync - dont know whats going wrong :/

Are you following the different starting moves on NM? https://www.deadwoodjedi.com/speed-tunes-4/New-Budget-Maneater---3-Bosses-only-1-Comp shows that both ME and PK should start with a somewhat different rotation. That kind of thing could lead to going out of sync a number of cycles later, which could be the reason for your problem. 

Also, are you sure that your speed on stun target is exactly 121, not a bit higher/lower rounded off to 121?