JS Scipt... unable to add Ambient Occlusion channel ... possible bug in JS API?

Nearly finished an import/export plugin.
I need to add 4 channels to the default ones when creating a new project.

They all work... except ambient occusion. . Found the keys are not case sensitive. I can add "Ambient Occlusion" channel manually but need it in the script.

Even though the error coses says maybe it is already added, it not as I'm then able to manually add it.
Seems like a possible bug.

PS - Also tried AMBIENT_OCCLUSION