The quest "Atriban's Metamorphosis" appears to not show up as completed in the journal when events play out in a particular order, at least on my openmw version. I have attached screenshots of the journal and quest log showing that the quest is still open, and the order in which this bug occured for me. There is no dialogue option following up on Atriban's condition as the log implies, as this option seems to have been exhausted earlier.