The formatting will change after conversion via Calibre.
Anyway, the issue indeed seems to be that the page is too small. But, it is a bit more complicated than that. The size includes pictures and so on. It is the whole package. So, a small page with only text will be 'stuck'. A page with one line and a large image will not be stuck.
Lets see if I can create a bug-report to Sony. Probably they won't do anything with it, but still.