Sky now reporting it as well:
@GraemeBailey: Adam Clayton stalling on Middlesbrough move as he would rather join Brighton, who have reopened talks with Huddersfield.
Sounds like it's back on from a journalist for one of the clubs involved:
@reluctantnicko: Clayton drama ... did not turn up at Middlesbrough to join ... wants to go to Brighton ... Huddersfield unhappy at messing about. #chaos