Are you using Roon or RoonServer. If RoonServer then that has no graphical interface and will only show an indicator on the taskbar notification section that it is running.
If it is the Roon then are you getting an error message or something in the Windows log file?
In addition to Rugby’s suggestions, I have a few others:
Are you by any chance running other antivirus/firewall software on that machine? If you are I would make sure that Roon is added as exceptions there as well.
Does Roon work as expected when you try running it in regular mode (not admin)?
Thank you for your comments.
I was running Roon. Roon Server had the same result.
I’m thinking this is a borked Windows installation, as I am seeing some other windows related issues. A “repair” re-installation did not fix, so I am going to do a completely new Windows installation and try again.