Hi, I have exactly the same problem with my SatNav, it happened on two previous occasions but both times started working again after a few day but this time it’s been a few weeks. The weird thing is, the first time and now this time it manifested itself at exactly the same place which I seldom visit. I’m in Norfolk and there is still a lot of military aircraft activity around here but so far I’ve been unable to pinpoint anything although recently an Apache Helicopter flew very close to me while it was hedge hopping across the fields and it disrupted the recording of my Dashcam, I asked around and that is a common thing because of the electronic blocking equipment they use.
I too was going to try a disk undate although my car doesn’t have the separate head unit I’ve seen in other cars, only the 2 SD card slots and regular CD/DVD dash unit.
Did you so far have any success with updating or repairing your system?
Regards, Bruce