I played today for about 5 hours before even thinking to go check out what the Drifter had to say. My entire engram inventory is completely full of Umbral Engrams and I finally went to see him, but now he has another one to give me, before I can start using his machines to decode them. I can't take the one he wants to give me, and I can't get rid of any without taking the one he wants to give me, first. So now I can't get ANY engrams, I guess?