Had that happen on a Prestige run after we got his health all the way down on second plate. My understanding of the glitch is that if you keep shooting him after his health drops to zero it may cause this bug. I noticed while watching the video that you had done damage to him even with his health at zero just before his shield went up, so that may be the issue.

So first up: I had this happen to me multiple times and it is as annoying as it was for you. In my opinion the cause for this Bug is that the damage phase is over meaning none of the plates is active any more. Although you can damage Calus with your super when not standing on a plate (if I am right, not totally sure) the main damage comes from the players standing on the plates (that's how I think it' s supposed to work). So as a result you can't damage Calus when the plates are not active any more (which is just stupid) In my opinion the plates should be reactivated when Calus summons his overshield so this does not happen again. Edit: Another option would be to raise the number of skulls you kill which results in more damage meaning you can kill Calus faster before the plates become inactive. The strategy my team normally uses for this is either a 4-2 Ratio (4 people in dimension, 2 in Throne Room, requires good teamplay) or a 3-3 Ratio (like normally) but when skulls spawn, one person in Throne Room kills himself. To explain these strategies: The Skulls Ratio is based on the people in the Dimension and in Throne Room. The more people in the Dimension the more skulls will spawn trying to kill the players. If you are not comfortable with 4-2, you can also do the normal Strategy with 3-3 with someone killing himself because the game thinks that the dead person is in the Dimension meaning it creates a 4-2 situation without having a fourth person in the dimension.

Yeah this has happened to me before and it is also the reason why I stopped raiding I know your pain