nearly All fractal Cm's in T4 are bugged. on 100cm the bosses minions will spawn at 66 weird and be impossible to kill first pull of any instance . (making 100cm title unobtainable. )
on 99cm the boss will stand still first phase to 66% (blocking energy dispersal)
on 98cm. the second boss after her 66% phase will become a static glitched animation. (blocking marble bounce achievement)
i haven;t seen others posting about these but they are very annoying AND I hope anet can fix them quickly.
i do not know if there is something we can do to mitigate these bugs but in groups i have run (premades and pugs) the bugs happen every pull even with people unaware of them.
i hope this brings awareness to them so they may be fixed.
(ps: i promised a friend id help them get 100cm title and it is currently impossible.)