Glass material rendered as dark grey I am trying to render a glass material on a cup. But it looks grey after rendering. Screenshot of the render. (https://i.stack.imgur.com/cNMEc.png)

The material details are as shown.Material details.(https://i.stack.imgur.com/H8Z84.png)
Your issue is with the render settings. By default, Eevee does not calculate Screen Space Reflections, effectively disabling translucent/transparent materials.

You have two options, change to the Cycles render engine, or stick with Eevee and enable Screen Space Reflections and Refraction