There shouldn’t be, although the reason I mentioned the plugins is that it’s possible a plugin is overriding the default ordering for your WP install. If you turn off all plugins and the problem is resolved, you can reactivate one at a time to find the issue.
If you’re still having trouble after that, feel free to privately post your login credentials here and I’ll take a look for you.
When I set the order under ‘Quick Edit’ it does reorder correctly. There doesn’t seem to be any issue with the ordering (I set “Contact” page to 5 and it moved to the end of the page).
Is there some other issue or problem you’re having with the order? The subpages you have listed under “Home” obviously can’t be ordered outside of their parent page if that’s the issue you’re running into, but I suspect it’s not.