I have this issue on posts, not pages. If I disable Easy Media Gallery it resolves the issue. The console error shows me it’s failing in
https://buildblock.com/wp-admin/load-scripts.php?c=0&load[]=hoverIntent,common,admin-bar,heartbeat,autosave,wp-ajax-response,jquery-color,wp-lists,quicktags,jquery-query,admin-comments,sug&load[]=gest,jquery-ui-widget,jquery-ui-mouse,jquery-ui-sortable,postbox,tags-box,underscore,word-count,wp-a11y,post,editor-expand,thick&load[]=box,shortcode,backbone,wp-util,wp-backbone,media-models,wp-plupload,mediaelement,wp-mediaelement,media-views,media-editor,media-&load[]=audiovideo,mce-view,imgareaselect,image-edit,svg-painter,wp-auth-check,jquery-ui-draggable,jquery-ui-slider,jquery-touch-punch,i&load[]=ris,wp-color-picker,jquery-ui-resizable,jquery-ui-button,jquery-ui-position,jquery-ui-dialog,wpdialogs,jquery-ui-tabs,jquery-ui-&load[]=accordion,jquery-ui-menu,jquery-ui-autocomplete,editor,wplink,media-upload&ver=4.4.2
I’ve tried changing the lightbox settings via lightbox and highside.js and has no effect. Disabling Easy Media Gallery solves the issue for me, but that’s not an easy fix to implement site wide.