Following up here, since I just got done addressing the same problem in my 2016 C-Max Energi. My car came with the 2G modem installed. I received a service bulletin, and had it upgraded a year or so later.
This fix is relevant if you use the myfordmobile phone app or website and it has stopped updating. On my android phone the MFM app would show an "Updating..." top banner that never finished.
The battery charge and fuel tank information was incorrect and did not change. The Vehicle Locator information was incorrect.
Removing and replacing Fuse F67 in the block below the glove compartment fixed the problem. Ford is likely relieved, after doing without my car's telemetry for months.
You can find the location of the fuse in the owner's manual in the fuses section, beginning on page 209.
To access the fuse block, remove the small cloth trim panel under the glovebox by pinching and sliding down the two cylindrical black plastic retainers.
F67 is the 3rd fuse down in the 2nd row on my 2016 C-Max Energy. I used needlenose pliers to remove the fuse.
Due to the rather limited space for aligning the fuse legs, I had to fumble finger it back into place by hand.
