This is the gap behind most of the confused reviews. The reorder screen looks like it “sets the order of the site.” It sets the order of its own list. The blog, a category, a Query Loop, and a menu you arranged by hand are other lists, and each one has its own sort.
Two queries, two sorts
The reorder screen asks for published posts of one type, ordered by menu order, ascending. The main blog asks for posts ordered by date. Both queries are doing what they were told. Saving a drag updates the menu order column. It does not edit the blog’s query.
Pages feel different because a lot of page lists already sort by menu order. You drag a page, and a page menu on the front moves with it. You drag a post, and the blog does not, because nobody asked the blog to use that column. The data changed in both cases.
Where people look, and what that screen is sorting by
| What you are looking at | What it sorts by |
|---|---|
| Reorder screen | Menu order, ascending. This is the drag |
| Posts → All Posts | Date, unless you click another column |
| The blog, or a post type archive | Date, until you change the query or turn on Advanced |
| A category or tag archive | Date. Menu order is not per term |
| Appearance → Menus | The order you set on that menu |
| A Query Loop that inherits the template query | Whatever the template query uses |
Advanced can close the gap for a whole post type, and it can also surprise you, because it rewrites queries you were not looking at. I would rather point one Query Loop at Custom Order. The steps are in Show the saved order on the front end.
If the reorder screen and the public page disagree after you have pointed the query at menu order, the next place I look is a sticky post, a second plugin sorting later, or a language mix. Keep order across languages covers that last one.