imported hatching/fills will not stay grouped within a draft group

[joebot]

I am trying to import some artwork from visio via .dxf export.  The visio artwork has some solid fills which correctly import as fills (solid hatching).  However, when I try to group the imported lines with the imported fills via Draft Group, the lines stick together but the fills refuse to be associated with the group.

Does anyone have any idea why this might be? Do you have any suggestions for making the fills stay with their associated lines? Thanks!