https://bugs.winehq.org/show_bug.cgi?id=52625
--- Comment #3 from C. Leu kle@bluewin.ch --- Thanks Stefan Dösinger for your fast answer!
Okay, so it looks that this is clearly a WineD3D related issue not a Mesa one. Will close in this case the Mesa bug.
And regarding Unigine Sanctuary it is strange that I can run it in native OpenGL mode only when Gallium Nine is present (in the corresponding Wine prefix). For whatever reason Unigine Sanctuary doesn't starts up properly in a standard Wine prefix. (It is hanging at the start-up screen.)
I know, this doesn't makes a lot sense. Maybe @Pavel Ondračka can confirm this behavior. ;-)
Unigine Sanctuary can be directly launched from the CLI in OpenGL mode via the Sanctuary_gl.bat file.