When attempting to connect to Systems using the RDP protocol the connection silently fails - absolutely nothing happens after the Connecting... window appears, it just stays like that "forever".
The issue started manifesting itself after the migration to Windows 8.1.
Upon further investigation I have discovered that the reason behind this has something to do with how mRemoteNG and/or the RDP component in the OS handles saved credentials. For example, I was able to make the connection to certain hosts once I cleared the username from the connection setting field in mRemoteNG. And yet, some other connections do have the username specified, but don't manifest the same problem.
Issue manifests in the same way on all Windows 8.1 Machines I have access to.
Windows 8.1 Pro/Enterprise x64