There have been several instances where the levers in the Cooling Tower, during the "main encounter," stop working. There is no prompt for players to pull it so they're unable to advance the encounter. The only option is to either quit the session or wait for the timer to expire.
In this case, we waited... but when the timer reached zero, multiple players crashed.
Video: https://streamable.com/88nxz8: (https://streamable.com/88nxz8)