iPad Pro 4th Gen doesn't see iRig HD 2

[kwunyeung]

I have an iRig HD 2 and it works fine with my iPhone but it doesn't work on my iPad Pro 4th Gen. I am sure that my micro-usb to usb-c cable works fine and it would support iRig HD 2 as my Macbook Pro recognize the iRig HD 2 perfectly using the same cable. After connecting to iPad Pro, the blue light of the iRig HD 2 is turned on but no app recognize an audio interface. From IK's FAQ, iRig HD 2 support iPad Pro. Are there any configurations I have to do with the iPad Pro or any other specific requirements that haven't been mentioned? Thanks!