Unable to open in Visual Studio shared apps created in Xamarin Studio

I am testing Xamarin Forms on Windows and Mac, and it looks like shared (universal) apps created in Xamarin Studio can't be opened in Visual Studio (2013 Update 2). Here is what happens:

1. Projects based on Portable app templates can be created and opened in either environment.
2. Projects based on Shared app templates and created using Visual Studio can be opened in Xamarin Studio both on Windows and Mac.
3. Projects based on Shared app templates and created using Xamarin Studio for Windows freezes Visual Studio on attempt to open them ("Loading project XXX...")
4. Projects based on Shared app templates and created using Xamarin Studio for Mac fail to load in Visual Studio with the message "Some data sources have regressed in their version number." Log file has further information about mismatch in ImmutableDictionary contents (see attached file).

I suspect this is a Visual Studio bug (since Xamarin Studio happily opens all projects), but it makes it hard to reuse solutions between environments.