I started playing D2 on Stadia and I decided to keep playing it on Steam. After I had to buy the DLCs again, I didn't want to at first and played a bit without them. After a while I did buy it, but in the meantime I had left the quest for the Bleak Watcher behind. Now when I wanted to start the quest again (with DLC), I couldn't activate it anymore because I supposedly already had it in my inventory.