We like to ask a few question regarding to your issue:
->Have you made any custom changes on core header.php file or any core templates?
->some where on header.php file of parent or child theme have you added
tag or somewhere wp_title are used?
-> try by deactivating plugin, sometimes plugin may create such problems. There on your site you are getting multiple title tag one is blank and another is with your site title and tagline. So browser is unable to carry second ones. see the screen shot: http://prntscr.com/an80gy
if this steps doesn’t help you , let’s discuss on live chat so we can make our work done so quickly. As we had already try to connect you on live chat but could not get any response from your side.