Little bit confused about Kepub conversion in Calibre

Hello.

I'm a bit lost in relation to the different extensions that allow to automatically convert EPUB to KEPUB. For a while, it worked well, when I clicked on "send to device", it sent a Kepub automatically. The series, authors, descriptions, playback percentage, playback time, special features worked well.

But now, 1/2, when I send an ebook, it's in Epub. Sometimes they are in Kepub but don't have all the features. Finally, last problem, I noticed a problem with a book in Kepub, while the problem doesn't exist with the same one in Epub. It is the Integral of "The Witcher". It's a very big ebook. The problem is this: some chapters (about one chapter out of four or five) is cut in two. Basically, it says something like "34/35 pages in the chapter". But when I get to the end of the chapter, I'm actually still in the same chapter. The reader makes a page break and the chapter continues, but the reader calls it a new chapter. That's okay, but it bugs me.

All this to say that there seems to be a problem with my conversion to Kepub. Here are my extensions on the picture.

In the end, my question is this: which extensions are necessary (and which ones are useless) to properly send Kepub? Which are the most reliable extensions, and which ones to remove? I use "Kobo Utilities" features. The rest, I'm not sure.

Thanks in advance!

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