Problems Assigning USB type to teensy 4.0

Hello there.
I have an issue with the arduino IDE, specifically assigning a USB type to my teensy 4.0 board. I want to assign it as a USBMIDI device, but for some reason it only shows serial under the ‘USB Type’ menu:

I am not sure what has caused only the ‘Serial’ usb device type to be shown rather than the whole list of options. Any help would be greatly appreciated.

It seems that paul has addressed this here: USBMIDI is not ready yet, and paul said he is “Planning to work on this and the other missing USB functionality starting Nov 25”.