Long story short, sherpaing friends through Last Wish. 5manning it because one of them couldn't make it. Smooth sailing all the way through.
I'm a supporter that the raid should be respected the first time through so for the first time through I insisted that we do Riven the intended way, eyes and all. After some trial and error we get to damage phase (i.e. the part where you go down the chutes again and shoot her boils). I'm rusty on legit Riven so afterwards we head back to our rooms and are ready to rinse and repeat. Adds are slow to respawn so I'm trying to remember if they give you a brief breather before restarting. Instead, Riven never comes. The elevators are still on. The doors never seal. Riven refuses to play ball.
I chalk it up to a weird glitch related to an Ogre pushing someone as they waited to go back down the chute and we run it again. After a few more attempts we get to damage again.
Same thing. Once is an oddity but twice is coincidence.
It was late for us so we left and we'll try again in the morning so maybe good old going to Orbit and reloading will fix it but in the case it doesn't, I thought I would bring it to light.
* Not shown in video, going back upstairs in crystals/blue side floor 2 had a *ton* of Taken Psions spawned in. I remember way back that there was an issue with Taken Psions causing a memory leak leading to Guitar errors or something like that and I'm not quite sure if this is what could be causing it
* The game is expecting all 6 chutes to be used for damage phase for some reason. I put less salt in this theory because low man was possible in the past and it seems like a weird thing to break in that regard, especially considering the encounter works normal up until where it should loop
* Like in Grasp of Avarice, something broke
Either way, thought I should shed some light on this issue. Not sure if it's easily replicable or we got into a glitched instance or something but if it's the former I find it funny that there's little to no documentation that I could find on this considering most people just cheese her anyways.