container dissapeared after accidentally stacking items in a brew barrel
 

This bug was actually posted at some point before.

Basically it works like this. If you accidentally put a stacked item in (possibly any) a tradeskill container and hit combine you get a red error message saying something to the effect of the item has been deleted.

The items of course stay on the screen and you can place them back in a bag one at a time from your cursor. However these are phantom items that you can no longer use to sell or for any sort of combine.

When it happened to me, I logged off shortly after. The next time I logged into the game the phantom items went poof along with the backpack they were in.

(I'm not trying to get reimbursed here for the backpack and tradeskill supplies obviously, they were nothing of great value. Just trying to show the steps to take so a dev can replicate it to verify the bug.)

Known and documented tradeskill containers bug involving inserting stacked items.
On top of this something similar happened in live.