I've just read a suggested solution that it might be related to a corrupted cache (thanks to @SportsKing812 for sharing it here: Solo Draft Still not working correctly — EA Forums):
>>>I found a fix on Xbox series x. You need to go to the Xbox home screen (big white button), highlight madden 21, hit the burger button on the controller and choose "quit". If you just hard quit the console while in madden, you will have problems with phantom/false losses that prevent you from playing all 13 solo games as well as all 6 solo draft games. Must be a cache issue.<<<
how to do clear/delete the cache on your device, see here: Clear cache to fix problems with your games
hope that helps. good luck
