I have the same issue on PC. Not sure what’s causing the issue, but my suspicions lean toward buffs not working as intended or stopping for some reason. I’ve also seen weird instances in dungeons where my DPS will drop substantially (like 20k+) for no apparent reason. I’ll be averaging 40-50k on enemies and then I’m suddenly way lower and it’s impossible to bring back up. There have been claims from others that set bonuses have stopped working in the middle of content, so my guess is this might be something similar.
I’m pretty sure it is still happening to me. Just a few minutes ago I had an issue where my max magicka was oddly low. I unequipped and re-equipped my gear a few times and the normal values returned.