Ron, I talked with Autodesk about this issue, It is definitely a bug in Rel 6. They wrote me friday, this is their response:
Erik Kurek
Avatech NSC
I have received word from Autodesk about the BOM not updating from an update ipn file. This is definitely a logged defect and apparently the in
an early release of SP-1 for IV6 which has not been released to the general public has fixed the problem so the solution will be out barring some
product stopping issue.
In the meantime I am going to close this ticket as being resolved
sorry I couldn't give you better answer, but at least the issue is fixed.
Erik J. Kurek
Mechanical Products Support Specialist
Avatech Solutions - National Support Center
(800) 808-7645 Fax: (402) 451-8007
Also, if you have to fixed it right now, I have found that if you delete the balloons and BOM and start from scratch,
the BOM will update. Hope this helps.