The problem is posted in this thread (
https://forums.ootpdevelopments.com/...99#post4800899), but a quick summary:
1973 season, historical lineups and transactions. A player who played in 1971 but not 1972 is missing from the Mets lineup. A player who changed teams in May is missing from their destination lineup. Looking closer, there is some sort of "shadow" league where the transactions seem to be happening and the only remedy is to assign them to the correct league via the editor. If there's any way you can help, please let me know. Thanks.