iTunes says my computer is already authorized, but it's not

I noticed that iTunes wasn't updating my purchases on my MBP so checked and it's not listed as an authorized computer in my iTunes account. But when I click "Authorize Computer" it's telling me it's already authorized. You can see from the screenshots that nnone of the the 3 computers listed are MacBook Pros. It's an old MBP running 10.6.8, don't know if that has any bearing. Anyone have any ideas?