You may have noticed that playing through the All-Star Weekend causes the schedule to be erased in MyCAREER. Needless to say, this isn't desirable.
Avoiding the bug before it happens
The workaround is to use the Play Next Key Game option, instead of Play Next Game. The bug should not occur when you do this, and Play Next Key Game will still allow you to enter the All-Star Weekend events (as they are apparently flagged as key games).
If the bug has already happened in your MyCAREER
If you've already experienced the bug and are now missing the rest of your schedule, you can try this fix as suggested by Unknown User:
https://www.youtube.com/watch?v=cNVDWaxhF8g