Symptm: In version 7.18 (this phenomenon does not exist in earlier versions), the previews of some dialogs, such as the preview of the Modeling > Extruded bar... command, are black.

Cause: The driver for the nVidia card is probably too old and does not have the Vulkan/OpenGL presentation method option.

Solution:

• Install the latest version of the nVidia driver from the website: https://www.nvidia.com/Download/index.aspx?lang=en-us
• From the nVidia Control Panel > Manage 3D settings, modify the Vulkan/OpenGL present method parameter by choosing the Prefer layered on DXGI Swapchain: