I got an Oracle Quest and I went to get the item. I bought the item, went back to the Oracle and clicked on the button to turn the item in. The site went down. I refreshed and it came back up and said I didn't have the item. I looked in inventory, not there. I went and bought the item again, went back to the oracle and she said I wasn't on a quest anymore.

Do you have a 15-point token in your inventory right now?

Similar problem: the Oracle "ate" my item but instead of completing the quest, the server-smashing terracoon came up. Unlike Gintama, I'm still on the quest, but my item has disappeared (twice!)

...and then, just moments later, the quest appears to have "retro-completed"; not only did I get a token (and presumably a stat boost, though I don't know for sure), I got an achievement for this quest as well.

Mine was delayed in appearing, just like yours. But it finally appeared there. :)