Thank you!
I tried via the live site via the wp-admin interface, as well as the site front-end login but no luck. The front-end login gives an error message, that the user name does not exist, please see the screenshot: https://i.imgur.com/iFxCvnv.png
One thing I noticed, that a container element as well as other elements are missing from the search output HTML code. Is the search shortcode used there, or the output somehow copied there via HTML?
If you are using a shortcode, then can you please deactivate, delete and re-donwload and reinstall the plugin? Please use the WordPress plugin manager, and no FTP to update if possible. I suspect some files may not have been updated correctly and the output of the older versions printed.