I have the exact same issue every time I start this exact cup. I have tried troubleshooting, but it happens no matter what I do, e.g. both when I start EA FC26 after my PS5 has been completely shut down, and when I first play another online mode in FC26 (with no problems) and then try the cup. It means that I miss out on one of my daily attempts no matter what; and after that I have to play all games in one sitting - otherwise I will lose the first game next time I try, e.g. I lost in the semis because of this bug.