"We have asked Bernt Haas to come back to Sunderland because personal terms have not been agreed between the two parties," a spokesman told the official Sunderland website.
"This is not a problem between the clubs, because a fee has been agreed with West Bromwich Albion.
"While it was announced by West Brom that the transfer was completed, this is not the case and we have asked Bernt to report back and he is due to meet with the club secretary."