Hi there, that’s not the issue with the shader action. It is a bug (glitch) of coppercube, a quick workaround or fix is to temporarily move all of your extensions from the Coppercube Extensions directory usually located here.
Documents\CopperCube\extensions
You can create a new folder in there, and move all of your extensions to that folder except for the Skybox shader, then just restart your coppercube editor, and it will load the shader action and will show the properties in the action panel.
once it starts working normally again, you can move back rest of the extensions from the temporary folder to the extensions folder back and it will just work fine.
Hope that helps!!