The Login PI Dashboard shows no latency data for RDP based connections.
Login PI uses metrics published by the remoting protocol. However, the Remote Desktop Protocol doesn't publish performance data until version 8.0.
See this article for more info: https://blogs.technet.microsoft.com/enterprisemobility/2012/10/09/remote-desktop-protocol-8-0-update-for-windows-7-sp1-enabling-a-great-wan-user-experience-for-windows-7-sp1-virtual-desktops/
Install RDP version 8.0 or higher.
Login PI - All versions
RDP 7.0 and below