I believe someone might need this even if this is a really rare bug.
I found out how to finnish the quest "test of the maestro" which was stuck for my character in the stage in which you should return to elder Filaur @ Dwarven Village, to receive his letter of recomendation in exchange for the item "Report of Cruma". I left filaur's task as the last one, so it was particularly frustrating.
The problem
the quest wouldnt show up Filaur's quest list box, making the delivery of Report of Cruma impossible.
So, how did i managed to deliver it ?
I realized something odd in my inventory, some quest items from earlier stages of "test of the maestro" quest were not deleted after i fininshed those stages, some items that were supposed to vanish after completing the task and talking to researcher lorain in cruma.
That was the thing which caused Filaur to "understand" the quest as still underway, and not completed.
The item Architecture of Cruma was still in my inventory even after talking to Researcher Lorain in the first stage of the quest, an item he should have took.
not only that, but I also realized that he didn't take back another item i forgot the name. heres an edited print screen:
After the destruction of all quest items with the tag [One-time] Test of the Maestro EXCEPT Report of Cruma, one should be able to talk fo Filaur again.
please be careful when destroying quest items not to accidentally destroy one of the marks which will be needed to change your class.
See you around, gentlemen.