Thanks Dale!
You have no idea how well that worked out. I posted the problem, went out and mowed the lawn, came back, problem solved!
And you get a double thumbs-up because you actually solved another problem I had not mentioned. I'll list it here in case anyone else runs into it. (And to make it easier to find, let's call it "tables don't break across pages".)
I'm sure you noticed that I had each note as a separate table. I originally had them simply as rows in a single table, but found that the Nook wouldn't break it across pages, so I could read only the first 8 or 9 notes; the rest ran off the page. I thought that was just a table rendering bug, and so made separate tables. That way, each was short enough that page breaks were not needed. But then, I noticed in another book, that a table (not endnotes)
did break across pages. So it wasn't all tables, just some of them. Now, the one that worked did not have a td width specification. When I removed the width spec from my endnotes per your suggestion, I also converted it all to a single table and now it breaks across pages.
Never in a million years would I have guessed that the width spec on one column would disrupt text flow in a different column
and keep the table from breaking across pages!
Thanks again!