This is an example of a correct no call and a legal play. In this example, White 5 is progressing the ball up the court when defended by Red 8. As he gets to the centreline he picks up his dribble with his left foot/toe on the centreline. The centreline is deemed to be part of the back court.
For a violation to be called for returning the ball to the back court, a team must be in control of a live ball in the front court initially. This means a player must be touching the front court with both feet while holding, catching or dribbling the ball in his front court. Thus, in this example, White 5 never has both feet in the front court as his left foot is on the centreline. Correct no call, play on.