Android device does not show up in adb list

Make sure your device is not connected as a media device.

I had a similar issue and solved with the following steps:

1. Disconnect device, and ensure to turn off developer options on the android device (if was previously turned on).
2. Connect the device via USB.
3. Turn on developer options on the android device.
4. Enable check box for stay awake.
5. Enable check box for USB debugging.
6. Open cmd (or MacOS' console), and cd where your adb executable is.

   Should be in SDK's platform-tools, which you can get from official-site: https://developer.android.com/studio.

7. Finally, run the commands:

   adb kill-server
   adb start-server
   adb devices
   

Now we can see attached devices.

Note that by following above steps, in most cases the USB-connection mode will be automatically set to MTP (Media Transfer Prorocol), but try setting that manually if it does not happen automatically.

Also, if above-steps do not work for you, try purchasing a new USB-cable, then retry above-steps (with the "new USB-cable").