I am having the exact same issue as elimariaaaa. The problem started about a month ago after an update to WordPress. Any time you load a page to modify it, the TinyMCE editor, “Visual” tab, is blank. If I click on the “Text” tab, the HTML is properly displayed and can be modified and saved correctly. If I click back on the “Visual” tab after clicking the “Text” tab, then the TinyMCE editor gets populated but any changes made are not saved.
I have tried installing they TinyMCE Advanced and WP Edit plugins and both behave the same way. I have disabled all plugins and switched to the default theme with no luck. I have tested in FireFox, Chrome and IE on multiple computers, from multiple locations, some of which had never been to the wp-admin page for my site. The only significant clue I have found is that the FireFox Web Console displays the following error message when editing any page, “Error: no such method ‘instance’ for autocomplete widget instance”.
Any light you can shed on this situation would be greatly appreciated.
