

That answers my question. If the USB dongle never disconnects from the machine, then I wouldn’t expect anything to show in dmesg, as the ‘sleep mode’ is likely occurring downstream of the USB dongle.
Are there any config utilities that came with it? Failing that, maybe wireshark the dongle and see if there is any sort of sleep/wake signal being passed back through to the host machine?
Eh, it’s one of those perpetual rivalry things where the answer will probably never be known, and doesn’t really matter except when it comes to petty squabbles between nations.