For continuous pagers the chapter transition page is always visible regardless of the current "transitionPageMode".
However, this was not properly checked and thus, it wasn't considered to be visible and instead of opening the previous/next chapter, the transition page got set to be visible first and only with the second hotkey press did the chapter get opened
Depending on the set reader width, the auto margin of the images took effect and separated the double pages.
However, for double pages, only the margin left/right depending on the page should be set, to properly center the pages without a gap between them
Depending on the screen size and e.g. the set "reader width" pages might not have filled out the full img elements size due to "object-fit contain".
This was caused due to the image wrappers flex container "align-items center" which slightly reduced the images width to some ".xy" number (e.g. instead of wrappers width 258px, the images were something like 257.83px)
In case two pages were displayed with different dimensions, the bigger page might take up more than 50% of the screen.
In this case the bigger page got limited to 50% which caused in to unintentionally get reduced in size
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