It is possible to restrict access to certain elements for an assessment setting. In order to do that, first the "Restrict access" checkbox needs to be checked, and second the desired elements need to be selected.
If only the checkbox is checked, but no elements were selected, saving the form produces a rather non-exepected error. Instead of displaying the error at the restriction checkbox, it displays the error for the "End date" field. See screenshot.
Error should of course be displayed at the corresponding area of the form.