This plugin breaks Modern Events Calendar by Webnus. It prevents MEC from functioning correctly in the backend such as selecting dropdown options, date picker, etc for events. It throws a bunch of console log errors when trying to do so as well:
Uncaught TypeError: Cannot read property ‘hasClass’ of undefined
at HTMLDocument.<anonymous> (load-scripts.php?c=1&load[]=hoverIntent,common,admin-bar,heartbeat,autosave,wp-ajax-response,jquery-color,wp-lists,quicktags,jquery-query,admin-comments,sug&load[]=gest,postbox,jquery-ui-menu,wp-a11y,jquery-ui-autocomplete,tags-suggest,tags-box,underscore,word-count,post,editor-expand,thickb&load[]=ox,shortcode,backbone,wp-util,wp-backbone,media-models,wp-plupload,wp-mediaelement,wp-api-request,media-views,media-editor,media&load[]=-audiovideo,mce-view,imgareaselect,image-edit,svg-painter,wp-auth-check,jquery-ui-tabs,media-upload,jquery-ui-droppable,editor,w&load[]=plink,wp-embed&ver=4.9.7:660)
at HTMLDocument.dispatch (load-scripts.php?c=1&load[]=jquery-core,jquery-migrate,utils,jquery-ui-core,jquery-ui-widget,jquery-ui-mouse,jquery-ui-sortable,jquery-ui-position,moxiejs,p&load[]=lupload&ver=4.9.7:3)
at HTMLDocument.r.handle (load-scripts.php?c=1&load[]=jquery-core,jquery-migrate,utils,jquery-ui-core,jquery-ui-widget,jquery-ui-mouse,jquery-ui-sortable,jquery-ui-position,moxiejs,p&load[]=lupload&ver=4.9.7:3)
at Object.trigger (load-scripts.php?c=1&load[]=jquery-core,jquery-migrate,utils,jquery-ui-core,jquery-ui-widget,jquery-ui-mouse,jquery-ui-sortable,jquery-ui-position,moxiejs,p&load[]=lupload&ver=4.9.7:3)
at Object.a.event.trigger (load-scripts.php?c=1&load[]=jquery-core,jquery-migrate,utils,jquery-ui-core,jquery-ui-widget,jquery-ui-mouse,jquery-ui-sortable,jquery-ui-position,moxiejs,p&load[]=lupload&ver=4.9.7:9)
at HTMLDocument.<anonymous> (load-scripts.php?c=1&load[]=jquery-core,jquery-migrate,utils,jquery-ui-core,jquery-ui-widget,jquery-ui-mouse,jquery-ui-sortable,jquery-ui-position,moxiejs,p&load[]=lupload&ver=4.9.7:3)
at Function.each (load-scripts.php?c=1&load[]=jquery-core,jquery-migrate,utils,jquery-ui-core,jquery-ui-widget,jquery-ui-mouse,jquery-ui-sortable,jquery-ui-position,moxiejs,p&load[]=lupload&ver=4.9.7:2)
at a.fn.init.each (load-scripts.php?c=1&load[]=jquery-core,jquery-migrate,utils,jquery-ui-core,jquery-ui-widget,jquery-ui-mouse,jquery-ui-sortable,jquery-ui-position,moxiejs,p&load[]=lupload&ver=4.9.7:2)
at a.fn.init.trigger (load-scripts.php?c=1&load[]=jquery-core,jquery-migrate,utils,jquery-ui-core,jquery-ui-widget,jquery-ui-mouse,jquery-ui-sortable,jquery-ui-position,moxiejs,p&load[]=lupload&ver=4.9.7:3)
at Object.<anonymous> (load-scripts.php?c=1&load[]=hoverIntent,common,admin-bar,heartbeat,autosave,wp-ajax-response,jquery-color,wp-lists,quicktags,jquery-query,admin-comments,sug&load[]=gest,postbox,jquery-ui-menu,wp-a11y,jquery-ui-autocomplete,tags-suggest,tags-box,underscore,word-count,post,editor-expand,thickb&load[]=ox,shortcode,backbone,wp-util,wp-backbone,media-models,wp-plupload,wp-mediaelement,wp-api-request,media-views,media-editor,media&load[]=-audiovideo,mce-view,imgareaselect,image-edit,svg-painter,wp-auth-check,jquery-ui-tabs,media-upload,jquery-ui-droppable,editor,w&load[]=plink,wp-embed&ver=4.9.7:4)
Now I have to find a new poll plugin. Hope this bit of info helps.