yes this is a known bug,
but you can still workaround it connecting nodes to the material in the node editor,
for example :
If you connect the texture output from a rgbSpectrum node to a the diffuse imput of the material,
then the RGB swatch for diffuse appears in Attribute Editor.
Well, this should be fixed in the next version (as Kai is replacing the old nodes),
but keep in mind that the plugin is still in alpha stage.
It is not usable for production, sometimes not usable at all,
because of the refactoring, some parts keep braking until they are replaced.
I have no idea when a usable version of the plugin can be released,
and it may be impossible for the plugin developer to estimate a realistic time-frame.