Fenix 5 not recognized by PC (Windows 10)

Since a few weeks, I have a problem with my Fenix 5. When I connect it to a computer (Windows 10), the watch is not recognized as a device (i.e. does not show up at all in the Explorer) - its also not shown in connected USB devices.

It does charge however. Tried on three different computers with two different cables....

Its not a problem for now as luckliy I can still cahrge the watch, however it would be nice so I can put beta firmwares on it (and sometimes I also put courses / swim workouts directly on the watch).

Any idea? Or is this directly a Garmin support issue?