I remember being in Tel Aviv for work, and pulling up maps to plot out a bike route from the hotel to the office. Only to find that the entire route is blurred out online. Turns out our office was a few 100 meters from something important to the IDF, so no map/route data available. Too far to reasonably walk, and didn't want to try a bike without knowing there was a reasonable route...
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.
You should compare notes with the trove of weird emails that Daniel at haxx.se gets (the curl guy) because his email address is in the curl license text appended in the fine print of a bunch of products.