CKEditor displays entire site page when rich text is switched on
The issue was due to a php code used in the donate button of the same page which got rendered in all wysiwyg fields. There was error in the code which disallowed the search to function properly. I was able to identify the issue using elysia cron which displayed errors  when search cron was running. Checking the logs helped me resolve the issue. 
Error in one page could cause the CKEditor to display the same page for all wysiwyg fields when switching on rich text is interesting. Thanks.