iPad Pro no audio with HDMI adapter

I purchased an Anker USB C to HDMI adapter (A8306041) which states is compatible with the iPad Pro 11 inch. When connecting to my monitor (Ben Q) I only get video, no audio. I have tried the following fixes.

ensuring volume on iPad, in app, in control centre and in sound settings is at max.

turning off sound restrictions

turning off bluetooth

resetting iPad settings

multiple apps and HDMI cables

Monitor audio is max and works with other HDMI devices.

Any help is appreciated,

Thanks,