Bug - Normal Fighter upgrade going wrong

[João Otávio Menezes]

I'm trying to upgrade a lvl 40 silver peacock to gold, but one of my other 4 sacrifice silver peacocks is said to be marked as favorite, but it isn't. I've tried marking and unmarking it, but i just won't work. What can I do? I've spend quite a long time to level it up, don't want it to be in vain.

 

[Bones]

That typically means that it's an active fighter on one of your teams, so double check where you've placed those locked fighters.