Superstar RB Never Subs Out

I'm trying to make this as realistic a simulation as possible, but I'm just getting frustrated. I'm playing an RB superstar, and it started out fine. The starter player 2/3 of the game, and I played the rest (about right). Once I became starter though, I never get subbed out. No matter how high I set the auto-sub out slider, I stay in. I am the only RB who gets carries unless I purposefully select a FB or QB run.

Does this happen to anyone else? Anyway to get around this?