Do you know if other moderators on your site have been approving the users? If that is the case, you should be able to see the approved users by filtering for Approved flags of the User type from the review queue:
The results that are returned will show you which staff member has approved the user.
If you are seeing the indicator that you have items to review, but there are no review items in the queue, you might be running into a bug that was preventing the review counter from updating when items had been handled by another staff member. I think that issue has been resolved in the latest version of Discourse. I’m not running into it any more on Meta.