Your Acronis data center is updated to Acronis Cyber Cloud 8.0.
You receive a "Backup is missing: No successful backups have been performed by the backup plan more than for XX days" alert from a backup plan that is not applied to any device (was revoked from ALL resources but not deleted).
Issue in the product, which was fixed on 28-Nov-2019
Issue was fixed on 28-Nov-2019. It is safe to clear previously raised 'fake' alerts. If you receive an alert "Backup is missing: No successful backups for XX days" from a backup plan that is revoked from all devices after 28-Nov-2019, please contact support