Unsellable champion that was hostile to my team

I was playing a game of Ranked TFT, and I tried to sell some of my champions before a carousel round. The champions were two Mordekaisers and a Fiora. The carousel round started as I was trying to sell them, and when I returned to my arena one of the Mordekaisers had been sold, but the Fiora had a red health bar, and was unsellable. In the next minion wave I put her out to see if she would return to normal, but she was treated like an enemy and attacked (and was attacked by) my other champions. She did not return to normal after the round had ended, and she remained on my bench for the rest of the game.