Values from select boxes are not stored for anonymous users

Using a new webform-5.x-1.3 installation, I created a form having various fields. One of them is a select drop down list with key|field values.

As an authenticated user, the value in the select list is saved and displayed correctly at the Results page. If an anonymous user fills in the form and submits it, the value neither is saved in the database nor is displayed at the Results page.