Right so the most important issue is that black terrain for triplanar.
Just for info, triplanar is either on or off, that thing from old SR with only marked layers having it isn't implemented. And I doubt with our GPUs we would notice, so not a priority.
I suspect this can be some issue in shader that only goes bad on nvidia cards. IDK but I don't have it on amd and neither on that poor integrated intel.
Yes, as you noticed triplanar goes off when no layer has that checkbox set. And it is also in Graphics options, tab Textures, under Triplanar for Terrain and Horizon set both to 0.
Can you also check if normal maps are there, after pressing F9?
So: can you load TestC13-Rivers, enable blendmap test F9 (to have R,G,B colors), disable vegetation V, enable fog G.
On Settings (Alt-E) press Right to set this camera view.
Now go to Layers Alt-T, on 3rd layer with enabled Highest slopes, take a screenshot, then disable Highest slopes, press Update, and take a screenshot (this should all be done with Triplanar option 1 or 2, should look same).
3rd case is with Triplanar set to 3 (3 = Normal) in options.
I'm attaching how it looks for me in all 3 cases
Let's then do another quick test on Mrs4-Platforms, with camera: View Left,
just go into Graphics options, tab Textures, set Triplanar for Terrain to 2 press F5 and do a screeshot, set it to 3 and do the same.
I probably need to check shaders output, but I need to enable them in code first and make another -RC2.