We had 2.8 when we worked with the theme, this issue occurred without us upgrading WP. When I disabled the theme I went into dashboard and upgraded wordpress and any plugins that needed upgrading. Made no difference, issue persists.
I don’t think we’ll get help from themeforst as we customized the theme (even thought it was mainly with images and ccs). However I will get in touch with the developer of the theme to see if he or she can help.