Hi, I completed the Mandel quest to slay 15 felids, turned it in, and the quest text in the book and in the free-floating popup that came up after accepting the follow-up quest instructed me to return to the dragon scholar to hand-in materials for making dragon treats ( quest I had completed the same day). I was able to turn the quest into the mayor normally per Mandels instructions.
Also you guys might want to add a little note to the collect dragon materials quest specifying that the materials have to be in your inventory to counted as collected - I put a bunch of stuff into my storage before logging off and almost ended up putting up a forum post that my quest progress had been reset after logging in the next day.