Zoom unable to adjust audio input

[Frank73]

For a zoom call I am trying to set up the following:

An Atem mini pro connected via USB-C cable to a MacBook Pro running MacOS 12.6.3

Zoom version 5.13.11

When I select audio input Atem mini pro, the slide for level audio input automatic mutes and I can't slide it to the right te raise the level of the sound.

This also the case when I use a Sounddevices mixer10T. Not responding on the level slider.

I've tried to select the Atem mini in the settings of the MacBook as default input.

Then in zoom select use same input as system.

No luck either.

I can only use the slider when the input is set to internal mic.

But on occasion the sound off the internal mic is not passed on.

WHAT to do?