Kobo Libra 2 - Starting page not n.1 after conversion

[Artemide]

Hello readers, I have a question, hoping is not too much stupid.
Today I've patched Kobo firmware, and transferred a book on the device, converting it from epub to kepub with "send to" function.
Converted book seems to be ok, but it not starts from page 1, first page after cover is 54 (corresponding to page 1 of epub version). I think to have default settings because I don't know very well how Calibre works, there is something I could check in order to avoid this behavior? Or it's normal?
Thank you in advance.