Finally found it!!!!

At the end of section 2, on the last line at the end of text that reached to the right margin was a "========" with no label.

It turned out to be the invisible section break. Backspacing beyond it did not delete it. But selecting it specifically and deleting it removed it and section 3 became a continuation of section 2.

I replaced it with a simple page break and now all is well.

Thanks guys.