I know that this question has been raised already a few times on the forum but I still have this issue and I haven't been able to find a solution.
I have created a fresh shared Xamarin.Forms project in Visual Studio 2015 on Windows. The first thing I did was update the NuGet packages from v1.3.1 to the latest version (v1.5.1-pre2). I then created a XAML-based XF page in the shared project and started editing it. That's when I realized that IntelliSense did not work.
I followed the suggestion given in this comment: https://forums.xamarin.com/discussion/comment/142079/#Comment_142079
I also followed the advice of @JamesMontemagno which was to unblock the files in Windows before loading up Visual Studio. However I still do not have IntelliSense. The screenshot below shows the experience I am getting.
Is there any fix on this? Having developed applications using IntelliSense for almost 10 years I feel pretty handicapped without it.