Hello @Marc Annous , Welcome to Microsoft Q&A platform.
As per the documentation for custom domain for a CDN endpoint after the domain name is validated, it can take up to 6-8 hours for the custom domain HTTPS feature to be activated. If there is an additional delay in enabling HTTPS feature (more than 6-8 hours) I will suggest that you open a support ticket regarding the same. If you do not have a support plan, please refer to my private message below. Thank you!