Hi all,
maybe the similar problem as in the the issues T275870 or T293708.
https://pl.wikisource.org/wiki/%C5%9Amiech._Studyum_o_komizmie
The e-pub containing all subpages can be generated only if the summary - template is used. Even if the links are subpages of the main page there are not included without the summary template.
The most suspicious character is the dot, less suspicious is the first letter in the name of the file.
Regards
Draco flavus