When generating a negative artwork, the shapes on the artwork layer will become clear (negative image) so you will not see the shapes that you have defined on "Anti Etch/Ground" and "Anti Etch/Power". Defining the copper voids as lines on Anti Etch will show up in a negative artwork output.
Not sure what you are exactly trying to do but if you copy the "Anti Etch/Ground" and "Anti Etch/Power" shapes to "Route Keepout/Ground" and "Route Keepout/Power" they will add copper voids on the plane shapes, granted the plane shapes are dynamic.
You could also manually add copper voids to the plane using Shape > Manual Void but I would recommend using Route Keepout shapes and changing your plane shapes to Dynamic, if they are not already. Using Dynamic shapes on a Negative artwork layer is perfectly fine with the added benefit of automatically voiding Route Keepouts.
Hope this helps,