On Xbox one you should be able to download every character to your HDD:
Maybe this works.
There is no fix for the offline certification issue on PC.
This thread:
has 1.5k views and still not a single word from the devs. For many people the game is currently online only.
Since this is the Suggestions and Feedback Forum, here is my suggestion:
Dear @developers please fix the certification issue and provide a working offline mode for both PC and Xbox One. Thank you 
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