If you switch Covenant’s while you have the quest “Anima Salvage” active you can no longer turn it in or abandon.
Yes I found that out today as well, but I picked it up in the new covenant did the quest and its hand in is the old covenant, which obviously is impossible.
Yup, same issues on Sargaras. Switched from Vampires to necrolords and can’t get rid of it, or accept the same quest from the necrolords.