Tizen Developers

Most probably the reason is Visual Studio version compatibility for 'Visual Studio Tools for Tizen'.

Visual Studio tools for Tizen Installation guide in Tizen Developers Site Mentioned, "You must have Visual Studio 2017" to install 'Visual Studio Tools for Tizen'.

https://developer.tizen.org/development/visual-studio-tools-tizen/installing-visual-studio-tools-tizen

Visual studio marketplace shows only the compatible extensions & tools for that version. For example, when I searched for 'Tizen' in marketplace from Visual Studio 2013 the result shows nothing:

But the same search shows 'Visual studio tools for Tizen' from Visual Studio 2017.

Yes I was using the latest build of VS 2017. It did finally show back up in the marketplace. However it has been one of the most frustrating processes trying to get it set up. Still haven't gotten the basic app to deploy to the emulator or device. But that will be in another post.