I'm assuming you are referring to the container that contains 388 machines in it? The View > Machines is dynamic, machines will show in whatever Machine Group last scanned the machine. The blank container is used for machines where the scans are from Agents, it's blank because there is no Machine Group to name it after. Do you have agents installed on these machines?
The View > Machines is dynamic, machines will show in whatever Machine Group last scanned the machine.
And that's why I always delete the group column with the column chooser. Otherwise I see groups like "wakelist" (machines I sent wake-on-lan to) and "testlist" (machines I was able to patch outside our normal window because no one was logged on). How machines were scanned has little relation to how I would logically group them.
Yes, the agent is installed.
Thanks you for you response.