Had similar issue - after GPS worked flawlessly for 1st year + (approx. 14,000 miles on new vehicle). Have watched this forum for last several months on the issue.
GPS sporadically, usually every trip, but not 100% of time, would show off-route, location arrow would be 200 - 500 ft. off to side or behind actual location. In urban areas, this caused GPS to constantly reset driving directions (suggested route) and erroneously pick up location on side streets, etc.
My dealer recently replaced the GPS "antenna module" (receipt being mailed - I will post part ID when received) - and issue appears to be resolved. Has worked for last 3 weeks perfectly.
Previous repair attempt included "reprograming" the module - which did not work. To assist dealer - I provided pictures of GPS screen when malfunctioning....
Will post repair codes for both service visits.
PS: also had previously tried the following (none worked): Master Reset (per Ford telephone support suggestion), twice tried the battery disconnect / reconnect (GPS would work for limited time < 100 miles). Also, dealer had previously confirmed software updates properly installed.