I think there is no doubt the club hasn't co-operated as much as it could. The question is if the club has co-operated as much as they had to.
I doubt very much the club held back information the PL was entitled to, after the court rulings.
But, even at CAS, the club was criticised for not providing UEFA with the evidence it presented at CAS, iirc saying that witholding information from the investigation that proves innocence for a later appeal makes a mockery of the investigative powers of UEFA. That was the basis of the CAS fine, I think. It will be interesting to see if the club appeals a fine for non-cooperation in this case and what the merits of each side would be, as this is still the PL process, unlike UEFA/CAS.