The problem was the angle. The sideline official is watching the ball there, and since it was on the baseline he was the only one with an angle for both on ball foul and Charge/Block. So he is watching the ball to see if a foul happens when going up while also watching the defender trying to draw a charge with his peripherals. Baseline charge is horrible to try and call because you have no help. The other refs have no angle to make the call and you're watching a 10 foot area from 2 feet away. He most likely couldn't see the movement if it was slight. It's why I hated ever being on a baseline because you have no help on any driving actions usually.