Found a solution (and so simple, really. Why I haven’t thought of that at the very beginning). Good grief!
When page break is inserted at the end of the paragraph like this:

The html code will be like this:

What I did is I remove the page break tag and put it at the end of the paragraph like this:

…and that solves the problem.
it's just a painful solution though especially when you have hundreds of pages that you have to do it manually.
This was a variation on a method that I sent tanborj and it was later found not to be entirely satisfactory. I have since sent this solution that provides an easy alternative to the method in RoboHelp which has a bug in it.
Open your CSS in a text editor. Add this
.break { page-break-before: always; }
(You can change the name of the first instance of "break" to anything you like but no spaces).
- In a topic go to what you want to be on the next page.
- Put the cursor at the beginning of that line.
- In the style dropdown you will find "break" or whatever you called it.
- Select that.
- You will see the page break symbol above the line.
See www.grainge.org for RoboHelp and Authoring tips

@petergrainge