I discovered that the front matter page style for the chapter template
incorrectly had the footer set to "same content left/right" when it
should have been different content (page numbers on outside margin, like
the other pages). This wasn't noticeable in the template itself because
there is no left-hand page visible, and for all the times I've worked
with chapters (based on the template) that did have left-hand contents
pages, I never noticed the footer error before.
I have now replaced the template file with the revised one here:
http://oooauthors.org/en/authors/userguide3/res3/OOo3_chapter_template.ott/file_view
If you d/l it and replace the previous one, when next you open any file
based on the template, it should ask if you want to update the styles.
Answer Yes and the footer will fix itself.
--Jean