There are multiple things it could be. First, check to see if anything is stuck into the USB port, like food particles, or any small metal item. Also go through Section 4 of your users manual. It has a bunch of good tips on how to use the USB, and things that might give it problems...Have a 2017 QX80. Getting a message on Navigation screen "NO USB MEMORY" Cannot charge my phone.
How can I fix it?