I suppose this can be due to the battery-saving mode of the eTap components. But with firmwares 9.0/9.1 there's an annoying on-screen message plus an alert beep, every time the Edge inform that a shifting sensor is discovered. In fw version prior to 9.0 the disconnecting/reconnecting was also present, but without messages and alert beeps.
The only way I can use the Edge is by turning off the shifting sensor... Since basically I upgraded from the 810 to the 820 because of the eTap connectivity, this is a little frustating.
I'm thinking of getting rid of the 820 and stay with the good, old 810