We’ve found out that the problem is independent of our theme, it comes from your custom changes in the .htaccess file.
Anyway you should contact your hosting provider http://prntscr.com/13b2r2w – the main problem is with this file http://prntscr.com/13b2uyw – when we return htaccess file to default settings like on prev screenshot then it works ok for admin – http://prntscr.com/13b2tqp
