Cases appear as read-only in Unified Interface or Customer Service Hub

When testing the Unified Interface view or Customer Service Hub, you may discover that you can't edit or create a new case even if you have System Admin rights. The problem isn't due to a lack of privileges, the problem comes about because there is a flag on the entity for "Read-only in mobile". If that checkbox is checked, the Unified Interface will not allow you to create or edit a case. Uncheck that box, publish the customization for Cases and you should be all set.