I've also been having issues with "GPS signal lost" message from the beginning. I only use Google Maps and it's usually in areas I would never expect which have good 4G LTE connectivity. The case is not the issue and it's usually near the door or on a mount. It's caused some serious issues for my wife and I when driving. Sometimes it will say it and return within 30 seconds, sometimes it will repeat "signal lost" 7 or 8 times and never connect, or sometimes it will say nothing and never reconnect. Even when I back out, clear the app, and hit resume or restart it will sometimes immediately say "GPS signal lost". It's complete ****, especially since my wife's S4 is absolutely rock solid.