While I am trying to add/edit the CiviCRM events, instead of CKEditor, the default textarea is displaying and also the HTML tags are display. But the CKEditor is working as expected for the Drupal contents.
I have checked on the Browser Console and I saw an error. The JS file URL is missing the actual domain, instead it takes the CiviCRM path.
GET https://sites/all/modules/civicrm/js/wysiwyg/crm.ckeditor.js?r=ufXP1 net::ERR_NAME_NOT_RESOLVED
Please check the Image link for more details - https://ibb.co/Nr4DcX4
I doubt this is something related to the paths and URL configuration. Please let me know if you require any more details to investigate this issue.
Thanks in advance!