Jimmy Butler has aggressively challenged Brett Brown on his role in the offense, according to sources.
Butler has been vocal in his contesting of Brown and his system, including a recent film session in Portland that some witnesses considered "disrespectful" and beyond normal player-coach discourse.
Brown has said he had no issues with the exchange.
There has been some concern over Butler's long-term viability and fit with the 76ers.
Brown remains a popular figure within ownership and management while Butler will enter free agency this offseason.
Rival teams believe Butler will eventually decide to take meetings with interested suitors in July.