I have a model with several UV layouts. Each layout corresponds to a material that is used for different parts of the model. Each of these materials in turn has a colour map and a normal map.
However, it seems Blender can only work with one UV layout at a time. I can only get normal mapping for one of the UV layouts, by clicking one of the Set rendering UV texture buttons, and not all of the layouts at the same time.
As an aside, this also seems to be affecting my ability to export my model. I’ve tried exporting my model a couple of times and it always seemed to only export information for one of the layouts instead of all of them, causing the model to have missing textures. I’ve tried Wavefront OBJ and Collada.