I'm using a lot my edge 530 to follow hiking gpx track. To save battery, i turn screen off when i don't need it. When it's then back on few minutes later, gps signal is back up and device often lose my route (no more route info, neither distance, and ascent remaining, etc..) .
Sometime my edge is able to get back on track after few minutes, sometime not...
To fix it, i always have to stop gpx track, and reload it. Route is quickly detected as soon as gps signal is up.