Just installed Fortran update 2 and its integration w/Visual Studio 2015 u 3 on 64-bit Windows 7.
Now when a document is opened in the usual way, from Solution Explorer, the tab is shown, but the document window is empty. The problem persisted even if VS was restarted, and happened with projects did not include Fortran sources as well as those that did.
When the system was rebooted and VS started again, the text editor works normally. So it must be an installer problem.