This does remind me of driving on the western edge of the Dead Sea in 2014 with my family. The only device we had that was capable of 3G-less navigation was my Nokia Lumia 620 (windows phone) with bing maps. I had maps downloaded for all of Israel and Palestine, but they refused to work at that particular spot. Still not sure if it was some kind of GPS/map blocking or just being at a really low altitude. Pretty sure that once we passed Jericho and turned towards Jerusalem, it started working again.