My 2019 fusion energi just did the same thing.
Kinda rehashing what others have said in this thread:
The ESN for the modem from the about section in the sync settings also dissapeared. Temporarily removing the #10 fuse fixed the problem (as in restored Value Charging) and the ESN came back. It appears the 3G modem is locking itself up trying to find a non-existent network.
I wish Ford would just push an update that permanently puts it into airplane mode but allows us to continue to use the smart charging/value charging features in our car. SYNC/MyFordTouch has always been a clunky mess.