My unm unkillable team works fine. 

Are you using Skull Crusher and Rosh too and if thats soo can u give me the speed of all your team ?

No, but if there is a change in clan boss speed, my team should not work

Have you checked your champs' true speed? The displayed speed are rounded most of the time so you gotta make sure with the speed calculator. Small fractions count when speed tuning specific comps. 

Did you upgrade a mastery that affects speed in some way? thats the number 1 way people wreck their unkillables in my clan

i run tower at 245, sc at 174 and i think

doom 186

fayne/brawler 17?

unkillable team u cant compare speed thats a diffrent set up

my ultra team speed still the same and is working fine, id say maybe without realising or remembering you've possibly added a glyth or something 

my teams stock standard not a unkillable team slow tune speed counter still works fine 

i dont have mastries that effect and there speed is tuned but yet somehow the cb boss catch up 

is there any speed tune for sc and rosh that can results in an unkillable team ?

Yes, I run Tower at 245 and SC at 174.  Works 100% on void UNM and NM, have not done any of the modifications for affinity changes.  What is your other speeds?  

I use:

186 Doompriest

175 Fayne

175 Brawler

I have subbed in 179 rhazin and 177 Frozen Banshe for fayne and brawler as well and those all worked.

I seem to have the same issue. 

I  am  having  the  same  issue   as  of  the  latest  update .  

Its simple:

UNM boss speed 190

NM boss speed 170