[BUG] Cant finish any delivery quest.

[NerZhulen]

At this moment on my lvl 31 character, I have three quests, where I am told to take an item to some recipient.
When I aproach the recipient and have the item in my inventory, the question mark above the recipient is grayed out, and I cannot finish the quest.

Please fix, it practically blocks progress for me, since questing is what I enjoy.

[NerZhulen]

UPDATE:
Putting the items in the bank, logging out, deleting WDB forlder, and logging back ingame, fixed the problem.

[AverageJoe]

I ran into this earlier with the "Stormpike's Delivery" quest: obtained it, deposited the quest item in my bank for a few days until I was ready to go to Loch Modan, then withdrew it and traveled to the questgiver only to be greeted with a gray question mark and unable to turn it in. Tried logging out and back in, disabling add-ons, deleting WDB and WTF folders in my WoW location, etc. but nothing worked. Ended up abandoning the quest, hearthing back, re-obtaining it, and flying back out to Loch Modan and was then able to turn it in. It's like the server forgot I completed it or something.