Sometimes the "Unmute" button is not active for the lecturer. We are not able to find the reason of it. But sometimes helps to re-share the screen (sometime several tries).
Hi @LiudaN If the muting tool is not working for a specific presenter, we would want to work directly with the problem PC in order to narrow down the variables and try to understand the point of failure. Please gather more details if you can recreate this problem again.