Page styles are reverting when saved/reopened

I have a book where the each page is left page, right page, or default. Default is mirrored. There is wide inside margin and a narrow edge margin as appropriate for each page. The first Default page of the book displays correctly as a right-page (i.e. a wide left margin and a narrow right margin) until saved and reopened, at which point that page and the first page of the next chapter (which is also Default) reverses its margins for no apparent reason. How do I fix this?