Details:

When attempting to create or edit a knowledge article, the ownership group field would show up and disappears.

Steps to Resolve:

The visibility of ownership group is controlled by the following OOB client script -

"OwnershipGroup:hide ownership groupfield"- /nav_to.do?uri=sys_script_client.do?sys_id=377f5cb753412300cc376512a2dc3436

Since its active, you do not see ownership group field on the form.

This is an expected OOB behavior.