Uncheck Bitmap Caching under the Experience tab in the properties of your RDP session
We have identified the CA DSM Agent Suite for desktop management as being the culprit for those who use this product. The remote control agent from this product seems to interfere with the modern GUI of Remote Desktop Manager. If you stop the agent, the problem goes away.
The tasbar on your remote system is hidden by the one from your local machine as shown below;
Simply set this option as shown below in the properties of your RDP session under the Display tab;