Yes, Peter is absolutely correct in this case - this screen usually appears when you’re connecting to Host running on the same machine as your Viewer. Please try connecting to Host located on a different machine and see if the issue persists.
Could you please double-check if you’re just logged in to the remote Agent (if the icon in your address book is green) or if you have a remote session running (for example, in Full Control connection mode)?
Please try adding the folder where you store and run Agent from to the exception list of any antivirus or firewall software you might have installed on your machine following one of the guides listed here.
Let us know if this helps or if the issue persists.
The active tab is populated when there is an active session running at the moment, i.e. it’s populated with Hosts and Viewers that are actively using RU Server. You can see more information on the RU Server’s Admin Console on this page.
Please enabling the Use legacy capture mode feature in the Host Settings -> Other tab and see if this helps to resolve the issue. After enabling the feature please make sure to restart Host to apply changes.