Simmons' absence was listed by the team as "reconditioning," and he did not travel with the team to Detroit for the game. The Sixers open the regular season against the New Orleans Pelicans on Wednesday.
Simmons missed training camp and the preseason so far in the wake of his offseason trade demand that rankled some teammates, raised the wrath of fans and left many puzzled why he wants off last season's No. 1 seed in the Eastern Conference.
The 25-year-old Simmons, a three-time All-Star, met with Sixers coach Doc Rivers on Tuesday.
Simmons has four years and $147 million left on his max contract -- though the 76ers placed in escrow $8.25 million due to the guard, and fines for missing games and practices could be subtracted from that amount.
Sixers president Daryl Morey and Rivers have been publicly optimistic since the start of training camp that Simmons would play again for the Sixers.
Simmons has averaged 15.9 points, 8.1 rebounds and 7.7 assists over four seasons with the Sixers.
The Associated Press contributed to this report.