Menue does not work

Options “Parent” and “Order” in my Page attributes do not work at all. When I try to parent a page to another one it does not react. When I try to change order of these pages in menu it does not work as well. I can write and assign any number in “order” field, but pages in menue are still in their own order and my new page is last anyway anything I would do. How can it be?

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