USB 3.1 not tethering

Hi everybody,
I discovered this strange behaviour of my USB3.1 (USB-C) port: if I connect my iPhone to work as a modem (hotspot USB), it is recognised by iTunes but doesn't appear as a suitable device in System Preferences/Network panel.
If I connect it to a USB3.0 port, everything is ok and I can connect to the internet.
Is this a known limitation related to USB3.1 in hackintoses or I missed something? Mine is a HS 10.13.6 running on a iMac 18.3.
Bye
Rommy