How do you get the permissions popup to come back? We have Nexus 5X running Android 6.  We are using a dongle to connect the USB C plug to a USB A device and when we did it for the first time we got a permissions popup to allow us to use the USB device.  However, when we try it now the device is not working and no matter what we do (unplug and replug, restart) we can't get the permissions popup back to allow us to the USB device.  Any suggestions?
Settings - Developer options - Revoke USB debugging authorizations.