Tomb of Sargeras - Floor didn't break after Avatar

[Eazykill-crusader-strike]

So, I was just doing Tomb of Sarge mythic on my assassination rogue and I get to Fallen Avatar.
I nuke his behind to oblivion and loot him as his corpse falls through the floor leaving me behind.
Now for those that haven’t done Tomb of Sargeras before, Fallen Avatar is supposed to break the floor, which admittedly, I had forgotten.

So the floor never broke, I did some researching and yes, you can still get down there by killing yourself in the elevator just before you arive to Fallen Avatar. Thing is, Khadgar and Velen are supposed to open a portal after you defeat Fallen Avatar to port you to K’J’s ship buuuuuuuuut since you didn’t do the fight properly dadger never shows up to open a portal for you.

I’ve tried reloading, killing myself and leaving the instance, reset instances and re-enter but no succes.

Which means you cannot go kill the last boss.
@blizz, please fix it so that the floor always breaks or place a portal there regardless?
Also, someone suggested this may be because of the rogue talent Sudden Demise killing him off as soon as he reaches 35%.

[Brenwan-the-shatar (Brenwan)]

I’m afraid that’s an issue with the fight’s scripting. Start the fight, wait about ten seconds or so, kill the maiden, he smashes the floor, you both fall through, and you can kill him on his platform.

There are unfortunately a number of bosses where killing things too fast can mess up the scripting. Take Taloc for example, the first boss of Uldir. If you kill him too quickly the elevator going down doesn’t start moving. Thankfully in that case it can be circumvented through the teleporter. You either have to jump out the doors after killing him but before they close, or teleport out somehow, go back into the instance, and use the teleporter by the entrance.