As the OP, my question has nothing to do with the vehicle, it's
windscreen or the reception of good GPS signals. The other GPS app
was displaying a good reception of the constellations at all times.
It's to discover if there is a problem within Ozi-Android that needs
to be reported to Des.
With it working on the outward trip OK in the UK and on the boat
cruse, but not in a particular area of France and Belgium. With
identical results on the return trip, where it also worked in the
coach in Germany, but failed on entering Belgium.
I'm aware of a similar problem with the working of an aircraft
location program, that would not work within a certain lat/long area.
Correcting the software bug, removed the problem.