Imported Para Formats Don't Update Current Formats

[Nancy Allison]

Hi, all.
 
I'm using FrameMaker 10 in a Windows 7 system.
 
I've just imported a Header format into all the files of a book. Of course, this Header format is used only on the Master pages.
 
The new format does not overwrite the old unless I physically open each file, go to the Master page, and reapply the format.
 
Is this a known bug that I am suddenly only now waking up to?
 
Is there a workaround? Updating the book and saving the files makes no difference, alas.
 
Thanks.
 
--Nancy