Thanks for posting here, we’ll be happy to help. In your first post, it’s likely that the monitor did not show an active signal because the KVM switch is not sending the monitor information back to the Plugable USB 3.0 Display Adapter.
In your update however, where the adapter is connected directly to the machine it should work. So, the first thing to check is that the drivers are installed and that the cable to the monitor is not excessively (over 4 feet) long.
To see if your drivers are installed you can check in device manager and see if the device shows up under USB Graphics Adapters, if so, double click on it and check the drivers tab. It will tell you the version of drivers installed, or if there is a problem.
Here’s a link to instructions on how to run the DisplayLink Support Tool. If your device still isn’t working after checking the cable and the drivers run the support tool and forward the output along with your Amazon Order Id and the serial number of your device over to us at firstname.lastname@example.org.
With the log files we’ll be better able to figure out the best next steps.