This article makes it sound like things are not amicable between the League and the players:

http://www.jsonline.com/sports/packe...384300901.html

"On January 11, 2016, the league notified Messrs. Peppers, Neal, Matthews and Harrison that it had initiated an investigation following the airing of the Al-Jazeera America documentary, which raised serious issues concerning their possible violation of the NFL/NFLPA Policy on Performance-Enhancing Substances," Birch's letter said. "The players were further advised that, with their full and timely cooperation, the investigation would be conducted expeditiously and with minimal disruption.

"While the investigation has proceeded, we have yet to interview the players. We have attempted since early April to work through the NFLPA to schedule them, but despite multiple requests the NFLPA has failed to respond, except to seek reconsideration of the basis for the investigation. This continuing delay and avoidance has obstructed our ability to conduct and conclude the investigation.

"In fairness to all, including the players involved, we must move forward with the interviews. Accordingly, this will advise that the interviews of Messrs. Peppers, Matthews and Harrison will be scheduled for the first day of their respective training camps, and the interview of Mr. Neal (free agent) will take place on or before July 22.