Hello - not sure if anyone has had this problem or not. Subject line pretty much says it all.

I've done most of the quests, and am now going back and completing ones I didn't bother with.
My team is level 60. (K A C S)
I didn't bother going into the sewers until now (level 60) as I don't have a thief in my party so didn't bother.
I received the quest to steal the vase, but its not there.
Did I wait too long to get the quest? Anyone else come across this? Anyone know how to 'get' the vase to show up in the Manor? I saved before going in, so have reloaded a couple of times, but every time the vase isn't there.
From memory it should be above the fireplace in the little room beyond the dining table?

Correct, it is above the fireplace as a free standing thing. You should be able to see it, though perhaps not right click it (I don't remember, and I don't have a save at the appropriate point). Did you try facing the fireplace and pressing the space bar while standing close?

Edit: Also, consider a trip to the Seer to ask about lost items.

Thanks for the suggestions Bookwyrm627.

I went back and tried your suggestions, but with no luck. I'll just do some other things in the game and see if it will somehow appear next time I go to do that quest.

Are you using the Greyface patch? If not it might just be a save/game breaking bug from the original that didn't get patched out.

Since it is a promotion quest for a class he didn't take, it isn't game breaking. He'll miss out on the quest XP from the two thief promotion quests, but that isn't at all necessary to finish the game.

I've never heard of this bug before. If nothing else, maybe the vase will show up when the area map resets. I believe the reset occurs after 2 years of game time from when he first entered Tatalia.