Apple Mail High Sierra loses the "bcc yourself" and the "sort newest first" preferences.

Was really happy with Apple Mail in Mac OSX Sierra. Upgraded to High Sierra, and now 50% of the time that I start Mail, it loses the "bcc yourself" and the "sort newest first" preferences. If I go into preferences I can set it back, but having to do this every other time I start mail is driving me bonkers. What's the fix?