You shouldn't have to create a book file.
In a single InDesign document, there are two primary ways to force a page break. In the EPUB Export Options, on the Advanced panel, in the Split Document menu, you can choose a single paragraph style, or you can choose Based on Paragraph Style Export Tags.
If you open the Paragraph Style panel menu and choose Edit All Export Tags, you can see all the paragraph styles, you can tag them with HTML tags (a good idea), and you can select paragraph styles which are to create a split.
Which of these two options did you use? If necessary, try the other method of splitting the EPUB into chapters, or breaks on a particular heading, like Contents.
I checked the file and the EPUB export options are set to split based on the Paragraph Style Export Tags.
The Edit all Export Tags in the Paragraph Style panel menu also show that both styles are set to split into new pages.
I'm going to try creating a book file and splitting the file into 4 sections; one for the cover, title page, toc and keep all the chapters together as another and see if that works.
Breaking the file into chapters solved the problem. Thanks for your help.
Great. Glad that worked for you.