I was having a problem on my main computer with the Host app. The Forum gave me the answer To test it, I ran the Viewer and went to another Host, on that machine I ran the Viewer and came back to myself.. Bad News.... after maybe 50 screens of "myself" came up I was able to cancel.
"Mirror" effect is going to appear if you connect from your computer to the same computer. But it is a good way to determine that the Host is working fine.