Header splitting documents are imported in the Main.WebHome and not in the resquested space and page

In 2.3 version, the documents which are imported with header splitting option are imported in the Main.WebHome page (behind its content). For farms, in subwiki, they are imported in the Main.WebHome page of the main wiki and not in its own Main.WebHome page.

The Office Import Application does not show any issue : there is the successful message "Conversion succeeded. You can view the result, or you can Go back to convert another document.". The link to the result links to a page which doesn't exist. Indeed, the importation doesn't create new page but imports the document in the Main.WebHome page.

Note that all the links to the splitted parts of the document links to pages which don't exist. They are also imported in the Main.WebHome page (and not in their own page).