Impression not recognizing CAD layers in blocks?

I'm taking my first stab at using Impression and have quickly run into a hurdle; it doesn't seem to import or recognize layers inside blocks.

I'm working on a site plan and all my building plans are blocks because they're repetitive. But unless I explode the blocks Impression doesn't recognize the layers specific to that block, so I can't control the look of my buildings.

Thanks for any tips on how to get this to work.