Arbiter not pausing when you pause the game

Title is exactly what happened. Playing by myself - not in any group - my mouse tragically ran out of battery right as the fight started (classic, I know) so I quickly paused the game - pause screen showed up, I stopped moving ... but the Arbiter sure as hell didn't. Proceeded to laser beam me in the face and I watched helplessly as my es and health rapidly depleted, unable to do anything (as I literally couldn't both in the pause screen and because my mouse wasn't working.)

I seem to be having a streak of the worst luck imaginable lately with this fight - not mechanic wise, but bug wise - (unable to re-enter demon form if I despawn out of it for some reason) but this one is just ...... so tragic. I feel robbed.
Please look into this -- thanks.

This happened to me as well, is this normal during arbiter? Let me know thanks