Are you using the 'public preview' version from Steam, as this should solve the black terrain issue. There was a report that discovered a user quit out of GameGuru before the new terrain plate had finished being generated for the new system so that could be the cause. To resolve this scenario, go into the terrainbank\lush folder and delete any texture_D / texture_N files you find then re-run, go to test game and select LUSH terrain and let it generate the texture plate fully (may take a minute) and then your terrain texture should appear.
PC SPECS: Windows 8.1 Pro 64-bit, Intel Core i7-5930K (PASSMARK:13645), NVIDIA Geforce GTX 980 GPU (PASSMARK:9762) , 32GB RAM