I was reading the manual, and noticed one thing.
You can only "release all the players and schedule inaugural draft" in preseasons.
OOTP Baseball Manual - General Functions
What day is it in your league?
If it is not the preseason period, then it is possible that you released all the players in a wrong way, like released all the players from your roster screen...
OOTP Baseball Manual - Roster Functions
I am not really sure, but t is possible that you MUST use the "release all the players and schedule inaugural draft option from your league function page, in order to have a proper inaugural draft.
I assume you checked the inaugural draft option at the game option page before you start the games, and then released all the players via roster function, instead of simply using the "release all the players and schedule inaugural draft" function at the league function page.
I think it is a possibility that it is causing the problem.
* These are all my pure guess, so do not forget to save your game file, before/if you try what I reccomended you here.