Go to System Preferences - Security and Privacy - Privacy tab - click Microphone - on the right Cisco Proximity must be checked. 

@darrenMack,   Can you check that Proximity has access to your microphone on your laptop. For our users on Mojave and 3.0 this was the issue they faced. 

An additional issue I have found with 3.0.0 is that when you have extended your display to an external monitor and also share via Proximity, the Proximity wireless sharing prompt will remain on your laptop screen and never disappear. This is a rare s...