This happened to me today as well. It was a Multi quest, but no reason it shouldn't have worked.
I am pretty sure its related to the Robe of the Lost Circle not being tagged correctly. There is a patch note related to the Robe of the Lost Circle's stats pre-kunark.
Someone on Red had a similar issue recently:
https://www.project1999.com/forums/s...d.php?t=349681