A domain was migrated from Expand to Plesk Automation (PA) using the panel-migrator tool. As a result it is not possible to manage custom DNS records (records that have not been created from the DNS template).
All DNS records that have been migrated are SYSTEM records which can not be edited. When you try to remove or change one of the records, you get the following error:
This record is used by system and cannot be deleted or modified. However, if change is really required, you can disable this record, and create alternative custom record.
This is considered to be a software issue with the ID #PMT-2070.
The issue will be permanently fixed in a future PPA update. In order to resolve the issue, please contact Odin Technical Support.