A few days ago, I noticed that the GPS date was wrong. GPSTest showed September 2002. And at that moment, Mapy.cz could not get a GPS location when it was in the foreground. When I reopened GPSTest (and Mapy.cz was moved to the background), the navigation actually worked fine despite the wrong date. But when I moved the app to the foreground again to actually see the map, it stopped working. Unfortunately, it didn’t occur to me at that moment that I could try to inject time data using GPSTest, which might solve the problem. I will definitely try that next time this happens. Anyway, from what happened to me, I think it is safe to assume that there are two problems. First, sometimes the GPS date or time is incorrect and needs to be manually fixed by injecting data in GPSTest. (I think this should be handled by the OS. I have never had this problem on any other phone.) Second, some apps seem to be sensitive to this issue and cannot get the correct location on its own.