As per the title, I've collected 200 lazy buffy marbles (and for the succeeding quest, 500 dual propellers as well). I accepted Sabitrama's quest, and as I tried to complete it (the reward screen showed up, telling me that I will receive 5000 exp), all that happens is that I get the quest complete animation and sound effect, but the quest is still there and the closed book is still hovering over Sabitrama's head. I have forfeited all other active quests and relogged, to no avail.
Try spamming Sabitrama with NPC Chat, and if this doesn't work, cc and continue trying. The quest itself is completable; what you're experiencing is a random bug.
