I am working on a 40 page document. Formatting is done consistently through
paragraph formats. I use no hard page breaks, only "section breaks to odd
page" at start of new chapters.

Midway through this work headings started appearing at the bottom of pages
instead of keeping with following paragraph, widows and orphans turned up in
body text, and page breaks appeared in paragraphs, despite the fact that my
paragraph style definitons explicitly say differently. All in all, it seems
as if Word has completely disabled all the text flow options.

This happens with all kinds of styles: heading, bullets, body text.

It is possible that the problem first appeared when I reduced the page size
substantially from A4 to roughly A5. I am aware that this can be interpreted
as a collision of rules (ie Keep with next, etc). This is not so however.
Paragraphs are generally short and Word has plenty of chances to get things
right.

I have tried all kinds of workarounds, such as redefining my paragraphs,
rechecking the relevent boxes (widow/orphan, etc), reconnecting with my
template file, etc. Nothing seems to work.

Ideas?