As noted in our email correspondence, this is the lightweight installer version of Visual Studio 2015. Do you know which modules I need to install? I currently only have C++ and the core modules.
We did not investigate this yet. VS detection is actually managed by an installer plugin provided by Microsoft (part of the WiX toolset), so by the time of the final release Microsoft will most likely resolve this on their side. Does the HKLM\Software\Wow6432Node\Microsoft\VisualStudio\15.0\InstallDir value point to the installation directory? If not, please try creating it similar to the previous versions. If yes, something more deep is causing the problem, so we would recommend installing the full version until Microsoft fixes the detection.