Follow these steps to ensure your microphone inputs are set up correctly in order to use OMS Communications (voice control) scenarios.
Check Permissions
Make sure you grant OMS permission to record audio on first request
Go Settings > Privacy & Safety > App Permissions > Microphone > Toggle on OMS
Check Mic inputs in OMS
Go to Settings> Voice > Microphone > Android Audio input
Check Quest 2 Microphone is on
Go to Quick Settings menu (press the O button on the right controller, navigate to time, wifi, battery), and find microphone option there. This should not be red (red=off)