[BUG] Base page slug before question permalink not working

I didn’t like the directory structure created by the use of “Base page slug before question permalink” [on] …

//domain.tld/questions/
//domain.tld/questions/users/
//domain.tld/questions/categories/
//domain.tld/questions/tags/

so I switched it off, because I wanted to see …

//domain.tld/questions/
//domain.tld/users/
//domain.tld/categories/
//domain.tld/tags/

But even after re-saving my permalinks a couple of times it still makes no difference.

How do I get rid of the “Base page slug before question permalink”?