I think I got similar but not the same issue. After the injury situation I simmed 'til the end of the season, And after my team was kicked from the P-Off the game crashes to the desktop. I got legit Steam version and online career. I used Limnono trainer for custom roster for MC, and firs time I increased my injury time from 5 to 25 days using trainer. And made some Trade Deadline moves like Boogie to NOP etc. I thought that was the reason, 'cuz some of them I made using old version of the trainer.
I revert my save from backup prior to edits, remade them using current version of the trainer and sim til the end of the season, replay P-Off (simmed some games) and got the same crash after POff ends.
So I revert the save one more time and sim one more time w\out any fixes using trainer. The same crashes at the end of the of the POff
And now after loading the save it's starting to load, then after few seconds I got black screen with music and then crash.
So I got 3 options:
1. The game cannot proceed to the 2nd season with custom roster (fix me if someone can proceed to the 2nd season using custom roster feature)
2. While I simmed I got several cutsceenes that should be in the 1st season but I simmed them and they can't proceed to the final cutsceen of the first season w\out them and the game crashes. SO fix me if someone has ever simmed till the end of the 1st season and successfully start 2nd one
3. It's just the game bug and it doesn't depends of trainer, mods (I tried to remove all mods), simmed games etc.