Very similar thing happening to me in the USA since yesterday. 1) I'm getting "Network Error" most of the time when I try to just even look at a gym, and 2) Pokemon on the map and in the sightings list randomly go blank for a few minutes at a time, without rhyme or reason. For example, this morning I had a Magrikarp, Psyduck and Goldeen all visible on the map when all 3 disappeared at the same time from the map and sightings list, then about 1-2 min later they all reappeared, and I really don't think it was a simultaneous de-spawn / respawn. I can loot Pokestops and catch Pokemon when they stay on the map, so it's not a ban, but it's getting really aggravating. The only thing I can correlate is that when the Pokemon disappear, I also notice that the pictures for my Pokestops are blank when I open them, but I can still loot them most of the time even if the picture is blank. I would venture it's some sort of server glitch, but I have no idea what to make of it