I received a response from SM tech support;

Quote - The Material Room will always work. The Pose room or other rooms, currently you must select the part or figure and then Drag the Material or Material Collection to the Part or Figure and hold over to apply.

The Project team is working on improving this function, but in the meantime they recommend using the Material Room to apply Materials.

So hopefully by SR1 it will be resolved. I'd guess based on the less than hopeful first response I got before the one quoted one - if it can't be fixed it'll go back to the way it was before(Materials only in the Material Room).