I was completing Saggitarius quests, and I think at about the 8th quest when I handed in the items, it kept going back to the screen requesting the items as if I had never given them. Then, it kept refreshing oddly in the quests widget between 8 and 15 (the limit) and then suddenly just went to 15/15 and I couldn't do anymore quests! So strange. Is this something people know about? (If so, sorry I must have skipped over it!)

It happened to me, but the issue is and I stopped doing quests in general and submitted a ticket in the process.

Is that, the reward page will give you items regardless if you actually done that quest.

In essence, its allowing you to complete the quest after the initial quest gets completed and then you get additional rewards, without submitting new items.

Same its happened to me on Quentins quests. So i've stopped for now.

Ah that's a bit of a shame since questing is such an essential daily for many of us! Thank you for the suggestion I might file a ticket then :)