Hi, Jim!
I found out that it all depends on how to fill in the search fields located on the main page wikitree.com or in the header of the site. If you fill in the search fields on the main page with the First name, then in the future, regardless of whether the First name is in the parameters, the search will return 58 positions. If you specify only the last name on the main page, then in the future, regardless of the presence of the First name in the parameters, the search will give 45 positions.
It turns out that there are not one, but two bugs.