Is it true Robert Carlyle is growing disinterested in the show?

I keep hearing that Robert is losing interest in doing the show and not wanting to be a part of it anymore. I mean I noticed also that he stopped appearing at conventions with the rest of the cast and the only recent appearances he's made is for promotion for the new Trainspotting film. He just doesn't seem as dedicated to the show as much as the rest of the cast is nowadays. I think he appeared at a recent panel thing but I'm not sure if that was OUAT related or Trainspotting related.