Using external mic in IOS (IPad pro 2017)

When connecting a USB external mic to iPad through USB port (which works perfectly fine for connecting other gadgets, namely an MPK), the ipad keeps on using the internal mic, disregarding the external. The mic is working fine and is perfectly powered while connected to the USB port . Just the iPad does not seem to acknowledge nor establish an audio input to it. Is there a way to sort this issue? I was looking mainly into using the external mic with GarageBand.