You can use a data explorer query to find the user you don’t see in the queue and approve them directly on their admin page.
SELECT id as user_id
FROM users
WHERE approved = false
AND active = true
This is what I did recently. I also get this message every 7 days. So I used the query and this was the result
And I verified it in the users admin page
But I still have to find out why the button doesn’t work in my case. I haven’t had a chance to look at it yet.
Hopefully the button just works for you. I think there is more than one bug which results in those notifications but no users in the queue. RGJ found something about rejected users, I reported a case where some existing users aren’t approved when the setting is enabled.