RH2017, Responsive HTML5, Indigo layout - TOC books with child links
I'm trying to work out how to set up Responsive HTML5, Indigo layout.
I have a parent project and half a dozen child projects.
I have a problem with the TOC from child projects not syncing with the topic displayed. It works for some child projects. Then it stops working.
So this is the TOC in the parent project.

And this is the output. All looks fine so far.
First level

Second level below "Opera 3 Help"

Third level
All great so far. Notice how the TOC on the right is in sync with the page displayed for the child project in the Administration folder. Excellent. This one works!

Now for another child project. Notice the TOC doesn't sync.


It should be here (I manually opened the TOC to show you).

All the other projects don't work either.
Any ideas please?
Thanks.
