Hi,
Well, it is a bit hard to tell without actually seeing the issue for sure. I can’t see the full query on the first picture either, so I can only guess.
First, I would try to remove the filter, to see if that changes anything, but since you say that the running query returns the users, it’s not likely. If you have any custom codes active in your functions.php file in the theme directory regarding the search results, that may also explain the problem. If the query returns the users, then the issue must be related then to the post-processing, so either a custom code, or something in the plugin post process.
There are only two conditions in the core search file, which may remove a user result, if the layout is ‘isotopic’ or ‘polaroid’ and the images are missing, but that does not affect your case. I am guessing a custom code, but it’s only a guess.