Are you getting any warnings? I had a similar experience this week and got "APS_w160 Software Update Required - schedule service". This was after the Holiday update installed. All autopilot/autosteer/cruise control functionality didn't work. Service tried to push the update again, and it did fully install, however it didn't work. Ultimately, I had to bring it to the service center so they could install.
**edit** just realized you're referring to FSD, not autopilot. Time for more coffee.