Developer-Dude
On any linux machine, open terminal and run this:
sudo dmesg -wH
(press Ctrl + C to get out of it)
New messages at the very bottom should pop up when you plug-in or unplug the phone.
Maybe it'll say unknown vendor id and unknown everything else. (bad connection or hardware issue like with the usb cable)
Try another usb port or cable.
Turn off phone and clean out usb port (if your tool isn't straight, careful to not scrape up the center thing too much in the charging plug)
Set usb-c to charging only then ON again (switching states can fix things some times)
reboot the phone and pc
Thes are in no particular order
P.S. some cables are charging only, no data, no connecting it to computer to get file/data transfers