Even without, odd/even next page Section breaks, it's quite possible that forcing the new Sections to start from a specified page # will have the same effect whenever the preceding Section ends on the same odd/even side the next Section starts with.

The behaviour is normal and reflects nothing more than Word trying to maintain a document output that is consistent with your page setup.

There is a way of having Word actually display the conditional blank pages, if you think that will help. The method involves the use of a field code at the end of each section to conditionally insert a page break if the page on which it occurs is an odd-numbered one:
{IF{=MOD({PAGE},2)}= 1 {QUOTE 12}}
or:
{IF{=MOD({PAGE},2)}= 1 "{QUOTE 12}¶
This page intentionally left blank¶
"}
To get the same effect for an even-numbered page, change the '1' to '0'.

Note: The field brace pairs (ie '{ }') for the above example are created in the body of the document via Ctrl-F9 (Cmd-F9 on a Mac) - you can't simply type them or copy & paste them from this message. Similarly, instead of the ¶, you should use real line/paragraph breaks.

__________________
Cheers,
Paul Edstein
[Fmr MS MVP - Word]