The "Challenge Kickoff" event is bugged.

I completed the entire event tutorial with my starting squad, but I can't sell the players for shards because the game says they are "in the lineup"—even though that isn't true; I removed them from all events and lineups. The only thing left is the "Kickoff Challenge," but I can't access it since I've already finished everything. Please fix this bug quickly, or else my squad will be glitched forever.