I'm fairly new with unkillable teams myself but here are a couple of issues I noted when setting up my team:

When you plug in your base speed, are you selecting the sets you were wearing from the drop-down menu (specifically for the 1 piece speed set Helicath is in)? I've noticed this does affect the true speed. If your speeds are tight this could desync you.

Check to make sure Occult Brawler isn't throwing it off with his A2 "If this champion is under 5 or more debuffs, grants an Extra Turn." I'm not sure if that extra turn pushes everyone's turn meter like the extra turn from a relentless set. It seems odd that everything runs perfect until turn 12.

in cal i putted all include sets, just calculator doesnt reflect aothar desync, 

i will disable OB's A2 and try. dont use relentless set on them

Also i can buff up aothar's speed to 177 - again cb cal shows that should tune

Try a run with OB's A2 off. I think that's what is de-syncing you.

without looking at the speeds or anything else, almost always gonna be this.

the extra turn is a tune killer. 

so is unlikely aothar's speed then

it seems that was aothar speed, boosted to 177, was runing fine against force CB, but something happen around turn 35 and get desync again. I could be that ninja had 5% conter attack on amulet, i think this also de-sync, as his a1 have a turnmeter boost against boses, so he cannot counter attack

yep, can't have Ninja taking extra A1s. CA is no bueno. 

now is a good time to make sure there's no masteries that are turn meter boosting any of your champions, too. 

Tested today, it seems to work now.

caviats:

Occult Brawler - disable A2

Ninja - cannot use any conter attack gear ( special amultets, rings or banners)

Aothar - needed speed boost from 171 to 177

Congrats. 

How's your one key damage running that team? 

I don't have Helicath yet, but he is on my "Wish List" 😁

get 39.4mil on 45 turn - but my champs have not gear leveled up on champs and aothar is not booked.

need to beef up UDK as he died first at turn 42 (i downgraded him to have lower health than HC) to be always stun target.

but as long as i consitently reach above 39 mil im ok :)

will do couple more runs and post results