Luc Mbah a Moute played in 67 games for the Sixers last season, and averaged a career-best 9.9 points per contest.
The Kings signed him to a one-year deal worth $1.5 million in free agency this summer, only to void the contract two days later over what the franchise claimed were injury concerns with his shoulder.
Medical records appear to indicate that Mbah a Moute is just fine, however, and Yahoo Sports/FOX Sports 1 NBA Insider Adrian Wojnarowski reports that the union is filing a grievance on his behalf.
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"The NBPA is planning to file the grievance to the NBA early next week , league sources told Yahoo Sports.
"Mbah a Moute has been meeting with NBPA executive director Michele Roberts in Johannesburg this week, where Mbah a Moute, a Cameroon native, has been medically cleared to play for Team Africa against Team World in the first NBA exhibition game in Africa."
"Mbah a Moute's representatives at Wasserman Media Group and NBPA officials, armed with independent medical examinations that produced playing clearances, are disputing the legitimacy of the Kings' process and the findings to declare a failed physical, league sources told Yahoo Sports."
Mbah a Moute was with the Kings for a portion of the 2014 season, so perhaps the team has some additional information based on his time there that it used to make the decision. But if he's indeed been medically cleared to play, it's tough to see Sacramento coming out on top once the grievance is officially filed.