I've had a small number of reports from users where their MyLEAGUE/MyGM save would reset when in their save and visiting the team select screen after selecting "Play Game" or loading an in-game save.
This is caused because of an edge-case bug that occurs when you select a custom roster using the Y/Triangle button in Quick Game. If that's one of the last things you did (independent of whether you played the quick game or not) before you load your MyGM/MyLEAGUE save, then it is possible that visiting the team select menu in your save might reset it.
To avoid this from happening, DO NOT load a MyGM/MyLEAGUE save after using a custom roster in quick game. Restart the game completely by closing the application and starting it again in between.
UPDATE: A user notified me to the fact that this is also happening if you use a Custom Roster in the Team Select screen for a Freestyle or other practice. So let me generalize this and say that if outside of a game-mode you've selected a Custom Roster in Team Select via the Y/Triangle button, DO NOT load your MyGM/MyLEAGUE saves without restarting the game.
This should not affect anyone that doesn't use custom rosters for quick game. In any run of the game where you didn't use a custom roster in quick game, you're not at risk of having your MyGM/MyLEAGUE save reset.
We sincerely apologize for the inconvenience and are looking to have this fixed without the need for a workaround as soon as possible.
I have to personally thank the community members that helped me track down this rare bug. Your help is immensely appreciated. Again, apologies.