Hiya,
Same problem here… Really anoying.
The preview port in the capture window is not always black, but the captures themself are usually entirely or sometimes half black.
System info:
Rhino 6 SR4 2018-5-10 (Rhino 6, 6.4.18130.19341, Git hash:master @ 51190de75f80526c68ef8bdf62938fe1eb6ccc8a)
Licence type: Commercial, build 2018-05-10
License details: Stand-Alone
Windows 7 SP1 (Physical RAM: 32Gb)
Machine name: L09197
Quadro K3100M/PCIe/SSE2 (OpenGL ver:4.3.0)
OpenGL Settings
Safe mode: Off
Use accelerated hardware modes: On
Redraw scene when viewports are exposed: On
Anti-alias mode: 4x
Mip Map Filtering: Linear
Anisotropic Filtering Mode: Height
Vendor Name: NVIDIA Corporation
Render version: 4.3
Shading Language: 4.30 NVIDIA via Cg compiler
Driver Date: 8-7-2013
Driver Version: 9.18.13.1233
Maximum Texture size: 16384 x 16384
Z-Buffer depth: 24 bits
Maximum Viewport size: 16384 x 16384
Total Video Memory: 4 GB
C:\Program Files\Rhino 6\Plug-ins\Commands.rhp “Commands”
C:\Program Files\Rhino 6\Plug-ins\rdk.rhp “Renderer Development Kit”
C:\Program Files\Rhino 6\Plug-ins\RhinoRender.rhp “Rhino Render”
C:\Program Files\Rhino 6\Plug-ins\rdk_etoui.rhp “RDK_EtoUI”
C:\Program Files\Rhino 6\Plug-ins\rdk_ui.rhp “Renderer Development Kit UI”
C:\Program Files\Rhino 6\Plug-ins\NamedSnapshots.rhp “Snapshots”
C:\Program Files\Rhino 6\Plug-ins\IronPython\RhinoDLR_Python.rhp “IronPython”
C:\Program Files\Rhino 6\Plug-ins\RhinoCycles.rhp “RhinoCycles”
C:\Program Files\Rhino 6\Plug-ins\Grasshopper\GrasshopperPlugin.rhp “Grasshopper”
C:\Program Files\Rhino 6\Plug-ins\Toolbars\Toolbars.rhp “Toolbars”
C:\Program Files\Rhino 6\Plug-ins\3dxrhino.rhp “3Dconnexion 3D Mouse”
C:\Program Files\Rhino 6\Plug-ins\Displacement.rhp “Displacement”