Group Sync Removes Member from Target if Removed From Source
When running a group workflow to sync distribution list from two domains, users on target domain get deleted (user accounts were added on target domain) if they do not exist on source domain. This happens only when the user account is mapped between such domains. Unmapping accounts avoids users from getting deleted on target domain during workflow runs.
When configured for 1 to 1 Members Attribute Sync, all objects in the mapping scope will either be provisioned or removed from the target group if they are mapped. Manual adds to the target group persist.