There was an incident at Hull's training camp in Slovenia back in early July that I believe got him suspended. But I don't think it's one isolated incident, more a combination of many. Supposedly turning up drunk for training on a regular basis, allegations about drug use, not turning up for training after heavy drinking the night before and then a toe to toe argument with Nigel Pearson.
I think it's been a done deal for a couple of weeks, Hull just been getting legal advice on how to get rid of him and not get sued.