TOC in Book not Working

I'm working on a document that's 750 pages long. I've created 12 individual documents in relevant sections and synchronized them within a book. I'm now desperately trying to create the TOC as it has to be an interactive PDF but it's not working at all I only get the heading when I run the TOC. This doc also has 3 TOC plus an index, I've tried the following;

1. I've synchronized TOC and Para style within the book
2. Saved docs and book, every time I do a change
3. I've replaced all the style sheets that are used to create the TOC (8 styles), just in case I messed up my naming convention.
4. I've all the docs open when I run the TOC
5. I've tested each doc separately by using the same TOC Style and deselecting Include Book Documents and it works in the individual docs
6. Below is a screenshot of the TOC Style just in case I've missed anything.

Any help would be greatly appreciated as I can't work out what's happening and I'm now on deadline.