Apply Master Pages not working

[Theresa de Valence]

I previously had master pages swapping correctly (by paragraph tag). 
However, since then I have copied the book to a new book (cross 
references working) and deleted many excess paragraph tags. Now my Apply 
Master Pages is not working correctly.

This is v 8 in structured frame, but the document is not structured. As 
far as I can determine, this shouldn't matter.

The only reason I can figure for the faulty Apply Master Pages is that 
some of the paragraph tags in the HTML Mapping Table do not exist.

Ideas?