You have to maintain control of the ball while rolling on the ground for the out to count. Umps made the proper call.
No sir. He touched the bag with the ball securely in glove. It wasn't until a second or two after the play when the ball dropped out. It happens more frequently at 2nd when someone is trying to turn a DP but drop the ball almost instantly after catching it. The runner is always called out.
Good start, Matt!