Hi! The space parameter for the viewdirection node seems to have no effect. It always return the view direction in world space. Are there plans to support this in the future? I am using Houdini 20.5.278.

No, this input doesn't actually do anything, and there are conversations on the MaterialX side to remove it because of that. If you need to transform the viewdirection, you can plug it into a mtlxtransformvector node.