Recovery Heart Rate is always zero

I recently switched to an Edge 840 from an Edge 520 Plus.  Since the switch, I've started seeing "Recovery Heart Rate" in my statistics (along with many other new values of questionable worth), but it's always zero.  I'm using a Forerunner 45 for heart rate data.  Is there something I should be doing to get Recovery Heart Rate results?

Edit: I checked activities on the Connect Web page, and they don't show recovery heart rate. So this appears to be an error in the Connect app, showing a field that isn't actually provided by Edge devices.