I have solved this issue, at least for my setup. The problem was I would use Garmin Connect Mobile to enable TE & PS but as it turns out my Edge 520 was overriding the GCM settings and disabling those functions. The solution was to use the Edge 520 to enable TE & PS and it's been fine ever since.
Also, unrelated, I have found that it's best to remove the Vector 3 from GCM altogether. Far fewer dropouts this way.
The problem was I would use Garmin Connect Mobile to enable TE & PS but as it turns out my Edge 520 was overriding the GCM settings and disabling those functions.
This is correct and we will try to communicate this more clearly going forward. Settings from the head unit (Edge, Forerunner, Fenix, or 3rd party computers like the Bolt) will always override and replace settings currently stored on Vector 3. The only time that the GCM settings will be used is if you are using a head unit or receiver that cannot send the relevant configuration settings (for crank length, for instance).
If you use multiple head units, then whichever head unit you are using on any given ride will drive the settings for auto zero, crank length, or cycling dynamics. If you use multiple head units at once, such as a FR920XT watch and an Edge 520 computer, then you should take care to ensure that the settings configuration that each will try to apply is the same.
Hey Garmin - glad that we both know what the issue is and how to fix it. Now if you would simply post this solution on the many threads where people have this issue it would be oh so helpful!
