I've just installed the long-awaited 2016.01 update (vNext). I've fixed all the most obvious breaking changes (i.e. which result in build-time errors), removed DockSiteViewModelBehavior, added IsOpen & IsActive properties, and set them to "true" immediately after adding a new ViewModel to the DocumentItemsSource. However, a new document / tab is never shown. There are no binding errors (or otherwise) shown in VS output. I've looked through the updated MVVM sample code and gone through the 'Converting to 2016.1" section of the helpdoc, but I didn't see any notes about what else might have changed to cause this. From the much-simplified MVVM sample code, it seems that just setting IsOpen or IsActive (after adding to the DocumentItems) should pop up the new tab.
Is there something else not in the documentation which might cause it to break in this way upon updating to vNext?
Thanks much in advance.