Boss won't drop items?

(Posting this in beginner forum since I only started playing a couple weeks ago and I'm generally still confused about a lot of stuff.)

I'm lv 49 so I went back and solo'd the Den of Rabid Wolves so I could mark off a couple quests, because I didn't look for a squad to beat it when I was a lower level. Rend Razorjaw dropped some cool items, but they weren't useful for my class. Then I got the minister arcane armor as a quest reward for beating it. So that was okay.

But then I wanted to go try and get some more minister arcane armor to drop, so I decided to try Firecrog Grotto. But when I beat the boss there, no items dropped. Thought it was maybe a fluke, or because I did two dungeons in one day, so I tried again today but did the Cave of Vicious with Poison Tail Occultist. Beat Poison Tail Occultist, but no items dropped from it either!

Besides the waste of time and potions, I'm just wondering how do I get bosses to drop items? Do I have to be on a quest for them? Or do I have to play with someone else that is on a quest for them? I just want that minister arcane armor... (and to stop wasting time going through whole dungeons to get zero items at the end).

Edit: Also, ignore my join date of 2008. I played only up to maybe lv 15 or 20 back then, then didn't come back until now and my character didn't even exist anymore.