0.61 The Drengin are gone (I killed them) and they are still asking for peace many turns later.

were they relocated to a planet elsewhere?

did you influence flip anything & leave a drengin starbase behind as a result?

i have experienced the same issue, they request peace every single turn starting from when they feel they are losing but it persists. I assume this will change like in GC2 they would ask for peace and would wait several turns to ask again but here in GC3 they ask every turn till they are gone. And the time this happened to me they persisted asking once they had no planets and reappeared in the Diplomacy screen, i traded for all of their shown belongings and yet they were still in the diplomacy screen and kept asking for peace every turn although there was no apparent property they had. (influence most likely was involved in my case fyi, it's been awhile so not so sure but they were persistent in peace when the only thing they had were their antiquated rally points.) Oddly enough, this was with the Drengin as well, me playing as Yor(i tend to only play the odder tech trees, i loved Thalan in gc2)

they may have had a ship on one my planets i flipped so i couldn't control but they still technically owned, i wish i had the save file still but unfortunately do not like my first bug post which was fixed by graphic driver update and could not replicate it after that

I remember experiencing this in beta 2, even after destroying all of the enemy's ships/planets. If you accept peace essentially nothing will happen, though perhaps it's caused by some random star base being alive somewhere?

Good questions, but no, I didn't flip any planets, and there are no Drengin starbases left anywhere. In fact, they had one and it got deleted when I conquered their last planet.

If they had been moved to another planet then that planet should show up in the Drengin's planet list, which it doesn't.

 And I turned the FOW off and looked for any sign of them, and found none.

I had the same issue yesterday in a game.  I had culture flipped a planet and killed off the rest.  Once I accepted their surrender then they stopped asking and left the diplomacy screen as well.

On a similar note, I also saw that once I captured two defeated races, Drengin and Yor I think, capitals then the UP met and I passed the influence bonus for UP members capitals and I got the bonus in the all 3 capitals (mine, Drengin, and Yor).

I submitted a ticket on this last week.    Not a game breaker, but annoying.

I did notice that after accepting peace they disappeared from diplo screen...but many turns later...they reappeared!    And I could negotiate with someone who had no ships or colonies!

Maybe this is a placeholder for the next step, maybe they are set to become a minor race after you conquer them, like a subjugated race?

Are you sure you combed the universe killing every last drengin. Maybe the united planet council is hiding them. This is obviously a bug I'm sure they will fix now they know exist. There are a lot of drengin out there considering they conquered everyone except earth. Why are you so set on the drengin genocide. Isn't it reasonable to let a few survive. Maybe the galactic council need to bring you up on war crimes. This gives me an idea as a possible referendum they need to bring the terrains up on war crimes because of the xandars.

I think Lord Kona should have a "Pass" button 

Same thing here. I'm working my way through their planets and he starts asking for peace and still asks for it after he's gone.

If the Drengin  or whoever have disappeared from the diplomatic screen, it's reasonable to conclude that they are history.   And when they reappear, as I mentioned, on the same screen many turns later, they showed no colonies, no ships, no starbases, nothing.