I recently needed to log into 14 servers at once, which I have configured in a group.
After opening all sessions, I lost access to the sessions pane, and RDM was giving a range of strange errors (sorry I didn't grab them as I was quite busy).
After completing what I was doing I closed RDM and reopened and it wasn't showing any connections in my data source. Editing the data source and then close and reopen returned my configured server list.
I am using 0.9.70.0 and will attempt to rectorate the issue when I have some time. The servers I was connoting to were a mix of 2008, 2008 R2, 2012 and 2012 R2, all on my local network.
It's look like a refresh issue after the crash. It's possible that allocating 14 servers at once the source of the error. Perhaps what we call a race condition. We will verify the FreeRDP code to see if something could be the root of your issue. I have to be honest it's not a simple problem to resolve.
David Hervieux