How did the refs miss this call in the Warriors rockets game?

Kevin Durant didn’t have just one foot out of bounds when he saved the ball before it made its way into Stephen Curry’s hands. He took three steps out of bounds along the baseline before knocking the ball back in. Klay Thompson recovered the 50/50 ball and threw it to Curry, who took a step in and knocked down an open mid-range jump shot to give the Warriors a 134-132 lead with 23.1 seconds left in overtime.

Nobody could believe it at the time, especially not the Rockets: