i didn't "see" this one happen, but i had to deal with the aftermath: tourney is playing the last hand before break, the player in seat 6 has folded his hand and left the table. the players in seat 4 and 7 wind up getting all in. the player in seat 7 wins.
when everyone returns from break, the player in seat 6 comes back to a seat with no chips.
upon some investigation, it turns out that when shoving the last pot to seat 7, the dealer included the chips from seat 6.
(of course, the push had gone through during the break, so the dealer who caused the error was no longer at the table, just to make matters even more difficult.)