The block has an associated extension dictionary attached to it. If you "vlax-dump-object" the object, it's HasExtensionDictionary property is set to -1 (true). I don't know if this is somehow affecting the block.
There are also 4 very small unassociated hatches and a single line at the centre point of the block.
when i inserted another instance of the block into 2009 scaling it uniformly and then changing it's x,y & z scales it doesn't exhibit the same scaling problems as the initial block.