How to correctly display a new field with wysiwyg in joomla 3.5 + K2?

Question

PHP

Hello!
Need help setting up a bundle of joomla 3.5 + K2.
The essence of the problem:
I am expanding the standard functionality of the K2 component, adding one more text field with an editor (introtext, fulltext + new champ).
The editor window is displayed, the content in the database is saved, but all tags are cleared, only the text remains.
I have never been a programmer, I need your help "to make everything work".