Why The Scheduler user does not have "Administer Project" and "Create Issue" permission?

This could be noticed in next-gen projects or with new Service Desk projects, when new permission schemes are generated. It is related to role created for apps: atlassian-addons-project-access. Here you can see the details: Project Role (atlassian-addons-project-access) has been added to our project permissions?

Make sure this role is included in both of mentioned permission, or specify system user "The Scheduler"