Auto-suggest search not working on popup list page

Update: I was making several changes, trying to diagnose the issue, and I actually landed on the wrong cause. What was actually happening is that no users had permission to view/list on that table. This was by design, as the table exists only for that one lookup and wouldn't have made sense in any other context. When I granted view permission to test the table, the auto-suggest began working and I assumed it was only on the table and not on the popup. But then I noticed it was also working in the popup! But when I removed permissions, it quit working again.
So bottom line: apparently when used in a lookup wizard, users can see the table even if they weren't given explicit view rights. But the auto-suggest will not work in that case. This is fine with me; I just had to grant permission and remove the links to the list page from the menus so users can't see it out of context.