C# Syntax Highlighting broken?

In my post here, the C# highlighting is incorrect:

• Randomly, the DXGI namespace isn't highlighted (maybe because all uppercase)
• bool and get are not recognized as keywords.
• set is recognized as a type name.

And I wonder why!

• The question has a [C#] tag.
• I even directed the highlighter that the big code block consists of C# code with <!-- language: lang-cs -->

What did I do wrong? :(