Career Ending Injury just happened and all set to 0.
 

First thing I do with each release/upgrade is edit injuries to set all CEI values to 0.

Since last update, I just had a player get a CEI but all CEI's are set to 0?

Not that it solves your question as to why it happened, but you can reset all leaguewide injuries or an individual players injury via the league settings or settings for the specific player. That will at least get the player healthy in your league again.