The tccutil command manages the privacy database, which stores decisions the user has made about whether apps may access personal data. This is similar to System Preferences>Security & Privacy>Privacy.
Even when the Mic has got the permissions to be used in eXp World, Mojave may still see it as unavailable. To use this command do the following in the MAC.
Click on GO> Utilities> Terminal. A white screen should pop up.
Type at the prompt tccutil and enter. You will see a confirmation message that the service was reset.
Open eXp World and login again. Mic should work in a sec or two.
tccutil reset service
Service Reset all decisions for the specified service, causing apps to
prompt again the next time they access the service.