Is there a glitch in the quest Revealing the Unseen?

I'm at the portion of the "Revealing the Unseen" quest (from the College of Winterhold) where I have to go to Mzulft and enter the ruins. However, when I try to interact with Gavros Plinius, the man slumped on the floor to the right when I enter the ruins, I cannot enter a conversation with him. According to the guide, as soon as I talk to him he should mutter some hint about the quest and drop a key that lets me through the door ahead.

I've tried talking to him, attacking him, pickpocketing him, and none of these things work. I've done other quests and then returned to try again, but still I'm unable to interact with him and get the key to enter the ruins. What can I do to continue this quest?

Try walking up to him and then just leaving the game running for 10 minutes, go eat lunch. He is scripted to actually initiate dialog with you, not vice versa, and for some reason the script is not firing up. I have had similar issues before and just passing time in the right location can on occasion fix this

The best advice I could give is to reload your last save before starting the quest. And if you don't have a recent enough one that you feel comfortable doing so than you may just want to leave that quest for a while and do a few others before returning sometimes these things just work themselves out.