I have a similar problem. All my notes have disapeared, both on the MAC PRO and on the iPhone. It is also impossible to create a new note on the computer, it just sits there without doing anything.
A new note created on the iPhone is synced to the computer but can't be found on the computer when you try to access it. Clicking on the note, in mail, displays the message "loading" and a grey spinning wheel. It keeps spinning on and on.It never stops and never displays an error message.