There was an issue where one had to click twice at the end of a chapter in the "double page mode" to get to the chapter transition page.
This was caused due to setting the "primary page index" as the "current page index" and thus, when opening the next page, it got changed to the "secondary page index". However, this page was already visible and therefore, there was no visual change.
Due to the way the pages got scrolled into view, the current page was not changed to the new page.
This then prevented the previous/next page to get opened via click/hotkey actions
schroda