Insert the block, redefine it so the attributes are no longer using the "special" attribute name Map is looking for. Sync your block using the Block Attribute Manager (BATTMAN). Put a field into that attribute that returns the viewports scale name.
If this is something you will use a lot, go edit the blocks in the drawing listed in a previous post and then you won't have to redefine the block when you insert it (you'll still need to add the field though).
The bar is scaled by 12 in paperspace? Can you use CHSPACE and just let it go to model space?