Suddenly end notes only will appear as foot notes

In Writer working on a document with only end notes from a cerrtain page each new end note that I want will appear as a foot note. This foot note will appear on the last page of the document, that is the page before the one with end notes. The foot notes that appear cannot be converted to end notes.
I have noticed that the pages where end notes were still possible have at all four corners of their texts rectangular hooks, but the pages where no longer end notes can be generated have in their corners slanted hooks. What do these mean, and how can I change them sothat maybe end notes will again be possible for the pages in question?

If your document does not contain sensitive or private data, edit your question to attach it and describe what to look for in it. In case of private data; turn it into “lorem ipsum” and make sure bad behaviour still occurs.

Thanks for willingness to study my problem. In the meantime I have solved it by moving all text on pages with slanted hooks in their 4 corners to the place from where the problem started, i.e. from where each time that I wanted an end note a foot note was created.
But I still would love to know how the problem could arise. What do at all the slanted hooks in the corners mean? Normal pages have straight hooks.
Attached are the pages with slanted hooks: Page with slanted hooks from which no endnotes can be created.doc
The problem started on the first one, right after the end note in the first piece of text. There appears also a small straight hook at the righthand side of the page. The second note on the page was meant to be an end note but appeared as a foot note.
To make sure that you get the page wit slanted hooks properly, I am sending you also a screen print: Page with slanted hooks, screen print.doc

Your text contains a section, which has a special property “Endnotes: collect at end of section”. Use FormatSections to view/edit the settings, or to remove the section (which would move its content to main text flow).