Just want to confirm I have the same issue.
J 1.6, CB 1.4
I tried with both Code Mirror editor enabled and TinyMCE (just in case it was a Code Mirror issue). I can save just a normal text area. Oh.. also tried in both FireFox and Google Chrome in case it was browser specific.
When this happens, none of the 3 toolbar buttons work, although the code is there. The only way out of the screen is to use another link at the top of the screen. I assume that there is a javascript error when the Editor Text Area field is chosen, because the SaveField function is there but disabled.