(This applies to 4.0.3 Windows version as it works fine on a Mac)
When you write a vertical CJK EPUB3 file(epubcheck-cleared) and set "page-progression-direction" element on OPF file to "rtl", the whole text aligns to bottom, making it unreadable.
Also can be seen with the sample file provided by IDPF here: epub3-samples/30/kusamakura-japanese-vertical-writing at master · IDPF/epub3-samples · GitHub
Weird, as it was tested on Windows 7/8 + MSIE 10/11.
A Japanese publisher, whom I'm helping their first ePub publishing, claims the same issue with the current Windows version 4.5, while I have no problem in Mac version.
As I can see from the previous post, seems like this is a long standing issue.
Does Adobe intend to address this issue sometime soon? Or are they even aware of this?
I wonder why no Japanese site complain this....
No Japanese publisher uses Digital Edition?