Repro
1) Open HDRP template
2) Go to lighting tab
3) Look at the drop down property Static Lighting clouds, notice its grayed out even though there are Volumetric clouds in the scene.

Expected result: Based on the name or the tooltip users can understand why the option is grayed out and be able to use the field.
Actual result: The property is grayed out. The tooltip says "Specify which kind of clouds to use...". Has no mention it must be of type Cloud layer.

Based of the name and the tooltip we should also allow Volumetric clouds as a dropdown choice. Or we must clarify the name and the tooltip so its clear what kinds of clouds user can choose from.