I have tried deleting the .sui, using the /ResetUserData flag, uninstalling and reinstalling VS2015, uninstalling every Visual Studio version and reinstalling VS2015, but no matter what I do, my Razor views are broken for editing. @model isn't highlighted in yellow. ViewBag has a red squiggly line under it. The Razor editor almost acts like a plain HTML edit. Only the @ and @{} get yellow highlighting, but there doesn't seem to be any knowledge of C# in the @ code.
How can I fix this? This is the feature that is the main part of my job.