Hi Stephen,
This should be possible. In my environment, I'm able to access both the flat and hierarchical presentations for a dimension, if I expand the dimension in the tree (see screenshot). I have noticed that the flat presentation is the default. However, if I expand and drag the appropriate hierarchy, I am seeing the hierarchy in the crosstab.
Are you able to expand the dimension and access the hierarchy?
Image may be NSFW.
Clik here to view.
Best regards,
Philip