I had this same issue a few years ago. Only ever happened when I was really hammering splits in the low teens. It was on 2011s, not the prodigy tho. I could duplicate it with several guns, both steel and plastic grips. It gave me fits. I never figured out exactly what the issue was or how I caused it… but ultimately I was having a new gun built anyway and in that gun I had the trigger kept a little heavier, at 3lbs rather then tuning it way down. I’ve since stopped shooting nearly as much as I used to, but I haven’t had that issue in a long time.
Sorry I’m not much help with this, but I’ll be following to see if anyone has any input- I’ve been curious about that ever since.