Cant Sell Cards, says there is Use?

Trying to dump some cards that I dont have in any of my lineups. They dont have the "no sell" tag but when I make sell order says "the item is currently in use. If you wish to sell unequip or unsquad it." Not only do I not have it in any squad but have never used it in any squad. What am I missing?

It might be automatically set for your event lineup even if you've never played events. Go in and make a lineup and remove all the cards you want to sell. Should be good to go after that