There was confusion about what exactly happened to Josh Hart when he headed back toward the locker room in the first half of the New York Knicks' preseason win over the Sixers. He slipped and fell while he had possession of the ball in what looked to be a non-contact injury. Hart slowly walked off the court, holding his back in pain.
He never returned to play, but the good news is that it was because he was ejected for throwing the ball in the stands (weak), and not because of his back. Brian Windhorst confirmed that on ESPN's NBA Today episode on Thursday, not long after the game ended.