I’m having the exact same issue.
I noticed some JS-errors which is likely the issue:
Failed to load resource: the server responded with a status of 403 (Forbidden): /wp-includes/js/tinymce/wp-tinymce.php?c=1&ver=4205-20150910
It seems my /wp-includes/.htaccess is the problem. If i remove that, everything works perfectly!
Anyone know a fix to the problem?
