Had same issue, however I'm using Macbook Pro (2016) which has USB-c only and I forgot my adapter at home.
Since unable to run adb at all on my development machine, I found a different approach.
Connecting phone with USB cable to another computer (in same WiFi) and enable run adb tcpip from there.
Master-machine : computer where development goes on, with only USB-C connectors
Slave-machine: another computer with USB and in same WiFi
adb usb && adb tcpip 5555
from thereOn master machine
deko$: adb devices
List of devices attached
deko$: adb connect 10.0.20.153:5555
connected to 10.0.20.153:5555
Now Android Studio or Xamarin can install and run app on the phone
Sidenote:
I also tested Bluetooth tethering from the Phone to Master-machine and successfully connected to phone. Both Android Studio and Xamarin worked well, however the upload process, from Xamarin was taking long time. But it works.