I was an invisible user recently. I didn't change any of my settings, but I had opened my browser to this forum, and then left the computer unattended for a while.
When I returned and started browsing again, I saw that there were two names on the user list. My name wasn't there, even though I was still logged in. The census said there was one invisible user. I guess that was me. Maybe the software does that when someone is logged on, but apparently not at his computer.
When you post your work, and no one comments, you
really feel invisible.