The exhibitor page exists and it has a path assigned to it:
Alias path: /Collections/Exhibitor-list/10-IS
Culture: English - United Kingdom
Name path: /Collections/Exhibitor list/10 IS
Live URL: /Collections/Exhibitor-list/10-IS.aspx
Navigation -> Menu action is set to Standard behavior
Another clue I discovered while testing: When moving the Exhibitor elsewhere it still redirects to the parent document, even if the parent document is different from exhibitor-list. But it won't redirect if the exhibitor is placed as a direct child of the tree root.