On both my Windows laptop and Mac Mojave 10.14.6 when plugging in the Fenix 5 to the USB port it is not recognized. Reboots, etc. have no effect.
What is the solution? This problem is getting to be really frustrating. Is it time to look for a different product? Not good. And, I've been a Garmin user since the Forerunner 305. I have never seen it this bad.