When create a Jira Next-gen Project and after that set up a Custom Field through Jira Settings, bulk editing component for issues is displaying that Custom field, however what I understand and I saw those custom fields should not be displayed in the Jira Project Settings > Issue type and I think as this Custom field is not shown on this place should not be displayed in the bulk editing process so I would like to know if this is expected since Jira Classic Project and Jira next-gen project are separated each other.