Try opening the attached solution, restore the packages and verify that it works. Now upgrade Rx using Nuget.
You will then get the following exception:
An exception of type 'Windows.UI.Xaml.Markup.XamlParseException'
occurred in App11.exe but was not handled in user code
WinRT information: Cannot add instance of type
'Win8nl.Behaviors.EventToCommandBehavior' to a collection of type
[Line: 14 Position: 70]
Additional information: Unspecified error
If there is a handler for this exception, the program may be safely continued.
You can either fix what causes this, upgrade to a newer version of Rx, or simply block newer versions of Rx from installing with this package.