The ajax edit doesn't work well with WYSIWYG editors. At this time am unsure why. The JS or jQuery binding for the WYSIWYG editor doesn't work when the editor is loaded in through ajax. Have added a bug ticket to look into this again, but last time there was no way for me to fix this and was due to how the WYSIWYG editor JS or jQuery binding worked.
forge.joomlapolis.com/issues/6668