Indeed. Turns out simple copying an EPUB and changing its extension from ".epub" to "kepub.epub" disables bookmarking.
If you don't want to edit the file, the right way is to use eg.
Kepubify, or Calibre + Kobo Touch Extended plugin
However,
EPubMetadataEditor didn't like one of the converted files: "EPUB Metadata Editor Badly formed OPF file.", although bookmarking works.
Even worse with Calibre: Both files trigger this error after converting the EPUB into KEPUB:
Code:
************** Exception Text **************
System.IndexOutOfRangeException: Index was outside the bounds of the array.
at EPubMetadataEditor.Form1.OpenEPUB()
at EPubMetadataEditor.Form1.Button2_Click(Object sender, EventArgs e)
at System.Windows.Forms.Control.OnClick(EventArgs e)
at System.Windows.Forms.Button.OnMouseUp(MouseEventArgs mevent)
at System.Windows.Forms.Control.WmMouseUp(Message& m, MouseButtons button, Int32 clicks)
at System.Windows.Forms.Control.WndProc(Message& m)
at System.Windows.Forms.ButtonBase.WndProc(Message& m)
at System.Windows.Forms.Button.WndProc(Message& m)
at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m)
at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)
--
Edit: To run it from the CLI
Code:
"C:\Program Files\Calibre2\ebook-convert.exe" "input.epub" "output.kepub" --authors "My Author" --title "My Title"