How come when controller runs out of battery sometimes it pauses and sometimes it doesn't

Died at the end of digistruct peak 6 because of this.

I tried a few times afterward but just can’t work up the motivation to do it again after getting so far, I hate that there is no save point anywhere, a good place would be after 4 assassins.

Probably I will give up again, usually Xbox pauses the game when controller battery runs out but sometimes it doesn’t and my character is left aiming upwards.