I got a Michael Taylor and Travis Arnaud from the EastCoast Bias box that have Prime shields and red boxes in my team Improve panel (also a Franklin Barreto). When I level them up only regular XPs get used, not the PXPs.
Edit--they're listed …
Can someone help me figure out the Prime XPs? I've accumulated a few thousand, but when I try to level my players (Bonus players, too) the XPs don't leave my Improve account. How do I use them?