Please In my site i have K2 and extra fields .
In extra fields i have some text and check box BUT i have also 8 textarea with editor
BUT
many times While writing content on the text area Fields in admin area and save then they DONT apears (in admin and also in front page)
not always. but I can not understand when

Hello,
You can try setting longtext for the extrafields set (Backup or do it in your test site).
Increasing PHP limits might also help.

I'm seeing the same issue. I used to be able to use the editor in my extra fields, but now K2 won't show any extra fields in the article edit mode if I have the editor turned on.

I'm not sure what you mean by setting "longtext."

Are there any other solutions?

Your's seems to be a different editor.
Not showing any fields at all, is most likely related to a JS error.

Can you do the following?
a) Use a different editor to rule out the issue of the editor throwing errors.
b) Open the console tab of the browser developer tools, to see if there are any errors.

That was it. RokPad doesn't want to load in the K2 extra field view. Thanks for the help.

You 're welcome Winston :)