Update:
I think I got all the cards. I say think, because the 68 prey cards are missing Light Side and Dark Side (Luna's cards) and there's a mystery card that I am still missing, but I don't think I'm actually missing anything. So, technically, I'm at 69/68 unlocked cards? Somehow?
No issues with the Pred cards though, 69/69 there. Maybe the Prey cards are meant to be 69 as well but you accidentally put Light Side and Dark Side in the same spot so it shows as one card that you're always missing even though you have them and they don't appear as "New!" in card choices anymore?