I contacted technical support because I thought the ACP Member Search function wasn't working correctly.
It turned out it wasn't a bug but a serious shortcoming in the User Interface when there are no matches for the search results.
I was looking at my member list working with various search criteria to shortlist dormant accounts that could safely be deleted. I was using Member Search rather than Prune because I wanted to preview the list. Fortunately I raised this as a query with technical support or the consequences for me could have been very dreadful.
Suppose you search for members with no posts, or those that haven't visited the site in a while. You're expecting to see a few members listed in the search results and you might then proceed to delete then. So what happens when there aren't any matches? I was pretty shocked to learn that instead of displaying nothing the response is to return a list of members and then in a pale background a message saying no results... the eye is distracted from seeing the 'warning' message because the list of members is displayed. There's nothing to say that the members being listed have nothing to do with your search criteria.
Please, please, if you have no results to show:
1/ display a very obvious box, say a big red box with a hazard symbol in it, to say no results were found
2/ don't show any other list of members
I can't think of any other filtered list that behaves in this way.
It's just asking for trouble!