Problem connecting to VMM 2012 SP1 from VMM 2012 R2 console

Hi. I have 2 VMM installations

 - VMM 2012 SP1 (highly available)

 - VMM 2012 R2 (highly available)

I have a management server with VMM console installed. On this management computer, I've uninstalled SP1 console and installed the R2 one.

The problem is that now I can't connect to the SP1 VMM server - for a moment, it is connecting, then I get the "Attempting the reconnect..." dialog for about a second, then it disappears and the R2 console logo appears again as if trying to connect again and the cycle repeats indefinitely until I manage to cancel the connection from the Attempting to reconnect dialog that briefly appears.

Same behavior occurs when I launch R2 console on the R2 management servers directly and try to access the SP1 server.

The strange thing is that it works the other way around, ie. I can connect to R2 server from SP1 console.

What's the problem with that? If anything, I'd expect not being able to connect from SP1 console to R2 server, not the other way around....

Any help is appreciated.

PS: there's an error logged in the eventviewer:

Source: .NET Runtime, ID: 1026, Desc: 

Application: VmmAdminUI.exe
Framework Version: v4.0.30319
Description: The process was terminated due to an unhandled exception.
Exception Info: System.ObjectDisposedException
Stack:
   at Microsoft.VirtualManager.PowerShellAbstractionLayer.PalRunspacePool.ThrowIfDisposed()
   at Microsoft.VirtualManager.PowerShellAbstractionLayer.PalRunspacePool.QueueScript(System.Management.Automation.PowerShell, RunspacePoolWaitCallback, System.Object)
   at Microsoft.VirtualManager.PowerShellAbstractionLayer.PowerShellContext.InternalBeginInvoke(System.Management.Automation.PowerShell, System.AsyncCallback, System.Object)
   at Microsoft.VirtualManager.PowerShellAbstractionLayer.PowerShellContext.BeginInvoke(System.String, System.AsyncCallback, System.Object)
   at Microsoft.VirtualManager.UI.Data.CacheInitializer.ExecuteCmdlet(System.Type, Microsoft.VirtualManager.PowerShellAbstractionLayer.ParameterSetBase)
   at Microsoft.VirtualManager.UI.Data.CacheInitializer.OnTypeInitialized(System.IAsyncResult)
   at Microsoft.VirtualManager.PowerShellAbstractionLayer.PowerShellContext.CallbackWithActivity(System.AsyncCallback, Microsoft.VirtualManager.PowerShellAbstractionLayer.PowerShellContextAsyncResult)
   at Microsoft.VirtualManager.PowerShellAbstractionLayer.PowerShellContext.RunspacePoolCallback(System.Collections.ObjectModel.Collection`1<System.Management.Automation.PSObject>, Microsoft.VirtualManager.Utils.ErrorInfo, System.Object)
   at Microsoft.VirtualManager.PowerShellAbstractionLayer.PalRunspacePool.ThreadPoolCallback(System.Object)
   at System.Threading.QueueUserWorkItemCallback.WaitCallback_Context(System.Object)
   at System.Threading.ExecutionContext.RunInternal(System.Threading.ExecutionContext, System.Threading.ContextCallback, System.Object, Boolean)
   at System.Threading.ExecutionContext.Run(System.Threading.ExecutionContext, System.Threading.ContextCallback, System.Object, Boolean)
   at System.Threading.QueueUserWorkItemCallback.System.Threading.IThreadPoolWorkItem.ExecuteWorkItem()
   at System.Threading.ThreadPoolWorkQueue.Dispatch()
   at System.Threading._ThreadPoolWaitCallback.PerformWaitCallback()