The Philadelphia 76ers fined All-Star guard Ben Simmons his $360,000 game salary for missing Thursday night's victory over the Detroit Pistons and plan to continue fining him until he cooperates with team physicians on his mental health and fulfills other basketball-related obligations, sources told ESPN on Friday.

The Sixers will again place Simmons' future salary into an escrow account, sources said. Earlier this season, Philadelphia released Simmons' money from escrow after he had been initially cooperative on a path toward returning to play.

Sixers officials believe that they have been supportive of Simmons' stated need for mental health assistance and that they are left no choice but for these actions in response to the three-time All-Star's refusal to provide basic details of his course of mental health meetings, evaluation or treatments or to accept consultation with any specialists arranged by the team, sources said. Simmons has worked with mental health professionals via the National Basketball Players Association.

For the Sixers and Simmons, this is the latest salvo in an increasingly antagonistic four-month standoff. Simmons -- with four years and $147 million left on his contract -- has requested a trade and has expressed no desire to rejoin the team.

Simmons has been showing up regularly at the team's facility for some daily basketball activity with coaches and individual teammates, but Philadelphia will begin fining him again for failures to participate in other requirements, such as strength training, film study and some presence at team practices and game-day shootarounds, sources said.

Despite Simmons' absence -- and with three victories without starting forward Tobias Harris because of COVID-19 -- the Sixers are 7-2 and owners of the best record in the Eastern Conference.

After Simmons incurred $2 million in penalties for a training camp holdout and limited return to the team, Philadelphia stopped fining him two weeks ago when he told team officials and teammates that he wasn't mentally prepared to play and planned to seek professional assistance.

In that time, Simmons, 25, has worked cooperatively with his own and team physicians on a back ailment but has told the Sixers repeatedly that he is unwilling to share information on his course of action in pursuing mental health treatment, sources said.

Simmons and his representatives have been unhappy with Philadelphia's handling of the situation since public criticism leveled at the guard in the wake of his poor Eastern Conference semifinals performance in June.

The Sixers have struggled to find a trade package that meets their asking price and tried unsuccessfully to persuade Simmons to return to play until a deal can be found. Philadelphia president of basketball operations Daryl Morey has said that the Sixers want a high-level player in return for Simmons, and that hasn't been available yet in months of trade discussions.