As far as I remember, he had an unofficial agreement to join Barcelona. I think this is the reason why number 7 was not given to Coutinho in the beginning since they kept it for Griezmann. He was even jeered and booed by Atletico fans because of this. In the mid of June 2018 he made a special video in which he informed everyone that he's staying in Madrid saying "My fans, my team, my home. Here, I would make history. At Barcelona, I would just be one more.". For me, this is more than enough not to want Antoine in Barcelona.
As I remember it, Griezmann and Barca had an unofficial agreement according to the media. Which doesnt mean shit in reality. I think if Griezmann acutal had agreed to a transfer, we wouldnt have it slide. I cant deny that the odds are high that Griezmann was 'in talk' with Barca about a possible transfer, which more or less was confirmed by ATM who threanted to sue / send a complaint to fifa. But what acutally went down in these talks we have no idea about, and my taking on this was: Griezmann never made a promise to transfer, but terms where agreed if he decided to transfer, and we would have informed what role he would have in the team and what our project for the coming years would be. Based on these talks Griezmann had a decision to make, which ended up with a documentary not only engineered by !Pique but also was the person who came up with the idea (i recall him stating that last last year).
So it hasnt been confirmed that Griezmann actually broke some promise with the club or was acting in bad faith. He made the video - which was kinda akward for us, but thats it. Personally i dont care too much about the video, its wasnt disrespectfull, more a testement that he felt ATM was a home for him and he wants to stay. The person who had an obligation to the club, Pique, did in fact 'fuck up' - so should we just shred his contract as well?