The TOC in Adobe Content Viewer displays one thumbnail with metadata per article. The article can have 1, 5 or 100 pages - yet there will be only ONE entry for that article in TOC. And if you mark the article as Ad it will not show in TOC.
On the other hand, in layout view (accessed with first button to the right) you will see all pages of your folio, including the ad pages.
You don't have any means to change this default behavior.
We are currently breaking this behavior apart so that you will be able to control visibility in the TOC independent from the ad setting. Currently, as Tomasz says, using hte ad button is the only way to control visibility in the TOC.
as you were saying "The article can have 1, 5 or 100 pages - yet there will be only ONE entry for that article in TOC". Does it mean that if I want the TOC to reflect my actual article TOC then I will need to split the article into multiple articles?