I was told the following some time back: -
Dyche had got wind of Gibson being tapped up and receiving text from another club (Watford, Norwich interested at the time) and wasn’t happy about it. Gibson was dragged into the office and was read the riot act by Dyche with the latter threatening to go the PFA or whatever about it. Gibbo replied that he still had all of Dyche’s text when he was texting him when he was a Boro player. This resulted in Dyche going for Gibbo and the pair having to be split up. Dyche refused to have Gibbo around the team.
How much truth is in that, I don’t know.