A family of Microsoft word processing software products for creating web, email, and print documents.
I neglected to mention that my document was originally authored in the browser version of Word. I have learned that this is simply not reliable for Table of Contents creation. I reluctantly installed the desktop version of Word, and sure enough there were some extraneous page breaks which I cleaned up, but the most important thing was rebuilding the TOC in the desktop version of Word. Then everything worked just as expected and the world became a happy place again.
Just to be clear, I didn't have to do anything fancy with section breaks, or anything else. I still have a page break after my cover page, then there is the 2-page TOC followed by a page break, then section 1.0 on page 4.
Moral of the story: only use the desktop version of Word if you want a proper table of contents.
My thanks to all who weighed in on this issue.