Using contenteditable in epub3

I'm having an issue using the content editable fields in the epub. For some reason the content editable doesn't seem to work on iBooks for Mac OS.

This is what I'm using in the html file.

<p contenteditable="true">&#160;</p>

And when I open the epub on iBooks on MacOS it doesn't allow me to type anything in there.

This works perfectly fine on iBooks for iPad.

Does anyone know how to fix this?