Did you pick someone up on the 31st? If you set up your lineup then did an Add/Drop then you have to reset your lineup. The changes you made to set the lineup will revert to the previous way. I have missed this sometimes, I move a pitcher into the starting lineup and then go pick up a batter. I stay on the top half of the roster/screen because that is where the batters are then I set the batters lineup and don't look closely at the pitchers lineup but scroll down and click save, totally missing the pitchers lineup has reverted. IT SUCKS, I know this and still miss getting in starting pitchers sometimes.