I used localhost from my desktop was test on XenForo 1.5.10, i check from admin panel with users list.
I'll created a account for "Test member and test member 2" has both still don't work button with "Ban user and merge with user" it's nothing, but i'll copy in link it's works fine. This is issue? I uploaded a screenshot GIF, here.
In the first instance, you should open the developer tools in your browser and go to the Console tab (usually accessible with F12).
This should log any errors relating to the opening of these pages.
You may also want to try right clicking the link and selecting "Open in new tab" to see if the full version of the page opens as expected, or whether there is any problems with, for example, the template being empty or any errors being displayed.
Mixed Content: The page at 'http://localhost/admin.php?users/testmember.2/edit' was loaded over HTTPS, but requested an insecure XMLHttpRequest endpoint 'http://localhost/'. This request has been blocked; the content must be served over HTTPS.
Yeah so that points to it being something related to the local web server itself. Although you're clearly using the http:// protocol, the web server appears to think it's loading over HTTPS and is therefore blocking AJAX requests.
You may want to look at using a different set up for your local server or attempt to retrieve support from whoever provides that (e.g. WAMP etc.).