I'm not sure when I first observed this problem, but I believe on a fairly recent version. The problem is that the viewer window stops updating/refreshing, and I need to close the viewer connection and open a new connection for it to work again.
Generally, I'll start some task on a remote server and expect it to finish in a minute or two. 20 minutes goes by, and I don't see the task finished. I look closer at the taskbar and see that the clock hasn't changed in the nearly 20 minutes or whatever. In todays case, it was like 40+ minutes where the viewer window was still open, but no refreshing of the connection was happening. I closed the Viewer's connection to the host, and the host was listed as "online" but not Logged On. I was able to get full control without having to close and reopen the Viewer app.
As I am multitasking and waiting for things to finish, having the Viewer window go stale on me really disrupts my work flow and wastes a lot of my time (this is at least the 4th time I've experienced this in last couple of months).
If the viewer connection window is staying open indefinitely without refreshing the screen or realizing the connection was interrupted and didn't reconnect, that's bad design or bugs. In the past, I could see when connections were dropped and it would attempt reconnecting (though, I did find it often failed to reconnect and I had to manually reconnect, but at least it was obvious the connection dropped and I needed to reconnect).
Please make it so that it successfully remains connected with refreshed display, or detect when it has failed to refresh the connection and drops/reconnects the connection properly.
In order to save bandwidth/traffic, the session may pause automatically, especially if you minimize the Full Control window. However, it should unpause and get back to normal when you return. Could you please verify that Pause/Unpause manually is working in your case? Here is a corresponding toolbar menu item: