When using update_field() you must supply the actual value that ACF stores. For example the documentation shows how to update a checkbox field with an array. In the case of fields types like a post object field, ACF stores the ID of that post object and not the actual post object. So if you are supplying the entire post object in the updated then ACF does not know what to do with it, or it is attempting to update the value and failing.
I’m asking you what the value of $team_code is because I can’t tell this by looking at your code. I haven’t got a clue what $team_code = rgar( $entry, '10' ); does.
