Just completed auric maelstrom mission A-I-II (power supply interruption). I got credit for not dying during it (auric storm surivor penance ticked up), but I did not get credit for the lights out penance (still at zero).
I had this too with non-auric malestrom. However it did count towards malestrom progression.
I think the issue is the malestrom missions don’t have the mission modifier for power outage, instead they have a malestrom modifier which includes a power outage as part of it.