I saw my Sonos amps listed there for a time. They were listed twice, one under Sonos and once under Airplay. Then when I quit Roon and restarted it, they’re no longer listed.
I have tried this on two different Windows 10 PCs. All my hardware are hardwired into the network.
Have you made sure to set both Roon.exe and RAATServer.exe as exceptions in your Windows Firewall and any other Antivirus firewall you may have?
You can use these instructions to check the Windows Firewall, and to locate Roon.exe and RAATServer.exe you can use the Database Location/Applications path.
I would add this as exceptions for both Public and Private networks to ensure Roon can perform the device discovery properly. Please let me know if that helps.