Crank locks with coaster brake
We recently got our 5yo a new Kent 18" Abyss FS18 BMX bike (I know, it's a pretty sweet ride) and we're having a weird problem. I'm pretty familiar with bikes but not coaster brakes. Anyway, we were riding today and every 5-10 minutes the pedals would jam up and he couldn't pedal. He would stomp it a couple times and it would unstick. When this happens the wheels keep turning freely but the pedals won't go. One time stomping on the pedal didn't unstick it and he had to get off the bike. I was able to get them unstuck after a few attempts by giving them a good reverse shove and then they were back to normal. Any ideas what's happening here?
Thanks,
Josh