It is a glitch in the game! A way I have seen it fixed pretty consistently is to AVOID IMPORTING A CUSTOM DRAFT CLASS (every single season). If you just so want the draft class anyways, the best way to fix it is to
1.) Download each individual player in the class's DNA.
2.) Use a auto-generated draft class
3.) Import each player's DNA individually.
NOTE: You would have to repeat this for every season in the MyLeague.
Hope this all helps you man! This game is a piece of trash.