Glitched Rob Gronkowski

I have 2 iconic Rob Gronkowski’s and I am trying to trade them up for the mythic gronkowski in the “what if” event trade. However 1 of the gronkowski’s is glitching and won’t go into the trade. He is not in my current team. And he is not locked in any way. I also have the other two purple groks. Has this happened to anyone else?? I’ve been grinding this event so much just to get him in mythic…