Problems with Edge 510 Cadence/Speed Sensor I have been looking online for a while on how to fix a bug with my Garmin Edge 510 Cadence/Speed sensor but no luck, and now I'm indoors training it's more important that it works (so I can get "speed" data to approximate power). It often drops out as in this ride and this ride for example. It seems I'm not the first to encounter this problem but I'm struggling to find a solution. Is there a fix?
I also have an Edge 510 (since ~3 months) with the same sensor, but I have not experienced this. I have recently updated to the latest firmware, which often solves similar issues with power readings.

Since you were riding at quite low temperatures, the capacity of the battery does decrease, but since the speed reading is fine I would not suspect the battery if the sensor/battery is not old (?).

There is a line/groove on both the sensor and the magnet -- check that they still line up properly. 

Check also that the sensor is installed in the correct orientation: the battery cover faces the wheel in my case. 

You should also verify if the sensor also acts this way when used indoors at room temperature.