Had a bizarre issue last night. FW 5.50
Went for a ride following a route I've done before.
Map was updating so GPS working but no turn by turn.
blue GPS track was all over the place.
all data fields updating except for AVERAGE SPEED which was 0, despite speed updating fine.
stopped the ride half way through, saved it and restarted the route as another ride
nav starting to work but still no average
finished ride and saved.
tried to upload over wifi but wouldn't upload.
powered down device, which just gave me a grayed out power symbol on the screen.
held down power button until device reset
neither of the rides were on the device. plugged into usb and not in the activities folder either.
The only thing I discovered was that I had other files in the "activities" folder. I'd renamed activities to things like "1stoct.fit, 2ndoct.fit"
deleted all the files from "activities" folder and device has been OK today.
very odd!