When I try to create a new page using Sahifa theme, the Page Builder interface is not loaded properly.
Chrome debug shows this error and disabling SNAP plugins solves the problem, so it seems to be a bug in SNAP plugin.

JQMIGRATE: Migrate is installed, version 1.4.1
js.js?ver=4.0.3:45 nxs_showHideMetaBoxBlocks:
js.js?ver=4.0.3:6 Uncaught ReferenceError: nxs_doManPost is not defined
    at HTMLDocument.<anonymous> (js.js?ver=4.0.3:6)
    at i (load-scripts.php?c=0&load[]=jquery-core,jquery-migrate,utils,jquery-ui-core,jquery-ui-widget,jquery-ui-mouse,jquery-ui-sortable,thickbox,quicktags,underscor&load[]=e,shortcode,media-upload,jquery-ui-position,jquery-ui-menu,wp-a11y,jquery-ui-autocomplete,backbone,wp-util,wp-backbone,media-mod&load[]=els,plupload,wp-plupload,mediaelement,wp-mediaelement,media-views,jquery-ui-slider&ver=4.8.2:2)
    at Object.fireWith [as resolveWith] (load-scripts.php?c=0&load[]=jquery-core,jquery-migrate,utils,jquery-ui-core,jquery-ui-widget,jquery-ui-mouse,jquery-ui-sortable,thickbox,quicktags,underscor&load[]=e,shortcode,media-upload,jquery-ui-position,jquery-ui-menu,wp-a11y,jquery-ui-autocomplete,backbone,wp-util,wp-backbone,media-mod&load[]=els,plupload,wp-plupload,mediaelement,wp-mediaelement,media-views,jquery-ui-slider&ver=4.8.2:2)
    at Function.ready (load-scripts.php?c=0&load[]=jquery-core,jquery-migrate,utils,jquery-ui-core,jquery-ui-widget,jquery-ui-mouse,jquery-ui-sortable,thickbox,quicktags,underscor&load[]=e,shortcode,media-upload,jquery-ui-position,jquery-ui-menu,wp-a11y,jquery-ui-autocomplete,backbone,wp-util,wp-backbone,media-mod&load[]=els,plupload,wp-plupload,mediaelement,wp-mediaelement,media-views,jquery-ui-slider&ver=4.8.2:2)
    at HTMLDocument.K (load-scripts.php?c=0&load[]=jquery-core,jquery-migrate,utils,jquery-ui-core,jquery-ui-widget,jquery-ui-mouse,jquery-ui-sortable,thickbox,quicktags,underscor&load[]=e,shortcode,media-upload,jquery-ui-position,jquery-ui-menu,wp-a11y,jquery-ui-autocomplete,backbone,wp-util,wp-backbone,media-mod&load[]=els,plupload,wp-plupload,mediaelement,wp-mediaelement,media-views,jquery-ui-slider&ver=4.8.2:2)
(anonymous) @ js.js?ver=4.0.3:6
i @ load-scripts.php?c=0&load[]=jquery-core,jquery-migrate,utils,jquery-ui-core,jquery-ui-widget,jquery-ui-mouse,jquery-ui-sortable,thickbox,quicktags,underscor&load[]=e,shortcode,media-upload,jquery-ui-position,jquery-ui-menu,wp-a11y,jquery-ui-autocomplete,backbone,wp-util,wp-backbone,media-mod&load[]=els,plupload,wp-plupload,mediaelement,wp-mediaelement,media-views,jquery-ui-slider&ver=4.8.2:2
fireWith @ load-scripts.php?c=0&load[]=jquery-core,jquery-migrate,utils,jquery-ui-core,jquery-ui-widget,jquery-ui-mouse,jquery-ui-sortable,thickbox,quicktags,underscor&load[]=e,shortcode,media-upload,jquery-ui-position,jquery-ui-menu,wp-a11y,jquery-ui-autocomplete,backbone,wp-util,wp-backbone,media-mod&load[]=els,plupload,wp-plupload,mediaelement,wp-mediaelement,media-views,jquery-ui-slider&ver=4.8.2:2
ready @ load-scripts.php?c=0&load[]=jquery-core,jquery-migrate,utils,jquery-ui-core,jquery-ui-widget,jquery-ui-mouse,jquery-ui-sortable,thickbox,quicktags,underscor&load[]=e,shortcode,media-upload,jquery-ui-position,jquery-ui-menu,wp-a11y,jquery-ui-autocomplete,backbone,wp-util,wp-backbone,media-mod&load[]=els,plupload,wp-plupload,mediaelement,wp-mediaelement,media-views,jquery-ui-slider&ver=4.8.2:2
K @ load-scripts.php?c=0&load[]=jquery-core,jquery-migrate,utils,jquery-ui-core,jquery-ui-widget,jquery-ui-mouse,jquery-ui-sortable,thickbox,quicktags,underscor&load[]=e,shortcode,media-upload,jquery-ui-position,jquery-ui-menu,wp-a11y,jquery-ui-autocomplete,backbone,wp-util,wp-backbone,media-mod&load[]=els,plupload,wp-plupload,mediaelement,wp-mediaelement,media-views,jquery-ui-slider&ver=4.8.2:2