Hi there! My name is***** am a computer professional with over 15 years of experience with both Mac and Windows computers, software, phones, tablets, e-readers, and printers. It would be my pleasure to assist you with this.
USB communication issues can prevent Garmin Windows applications from communicating with Garmin devices.
If a Garmin mass storage or MTP device is not detected by a Garmin Windows application, check to make sure that that the device recognizes the USB connection. Most devices will display an icon on the screen indicating that the device is communicating with the computer.
When a device is properly connected to a Windows computer, it will be displayed as a removable disk or portable device. To check whether Windows recognizes the connection:
Mass storage and MTP devices are both listed under Devices and drives in Windows 10.
If the Garmin device does not display the connection screen or is not recognized by Windows, try the following steps:
Note: I know that you've already done some of these things, I'm just listing them anyway for the sake of thoroughness.
Please give this a try and let me know if the device is recognized by the PC but not the Garmin Express software or not recognized by either.