Can't add body copy, after trying to save without it

[jobiddulph]

After erroneously trying to save an article without body copy, I would expect to see an error message saying that body copy is mandatory, and then be allowed to enter body copy and actually save the article.

If I try to save an article without body copy, the article doesn't save and an error message appears saying 'This field must be specified'. If I then try to add the body copy and click on Save and Continue, the body copy field is wiped and this error message appears 'This field is a required field which the client has no permission to write to'

As above, steps to reproduce are to create an article with title and excerpt, but no body copy. Click on save, then try to add body copy and save.

Publish v.3.0.0