When using the Cloud application on a Mac, when you start a presentation by default the presentation takes over the entire screen and you are not able to see the far end at all until you stop presentation. On a Windows PC when presenting, the far end is seen in a small window on the bottom left. By design the Mac Cloud application has this feature turned off due to extra resources needed. You can enable the Mini Player by going to the top left corner. Click on Lifesize > Settings > and check mark Show Mini Player When Inactive. See photo below for reference.
This will allow you to see either far end or local view on the bottom left when presenting your screen.
Global Support Engineer