My Art institute loan discharged. But my parents no.

My discharge happened the end of October but my parents art institute loans didn’t get discharged. I was told my parents would not be getting a refund because they took out a private loan thru Sallie Mae. Not a parent plus loan. (No idea why) my folks paid off that loan years ago but was wondering if there was a way to dispute that as well since the payments clearly show Sallie Mae was complicent with the Art Institutes. Anyone else know of any parents whose private loans got discharged-refunded?