We use Windows Cluster File Services, hosted on Windows Server 2019. BackupExec agent is installed on all servers of Windows File Cluster.
Several disks are shared on File Cluster.
Each disk is backed up via separate job + each disk is presented as a separate resource in DNS and on FIle Cluster (though located on same server)
1 of the disks is backed up without any problems.
On the second shared disk - BackupExec only copies 15GB of data out of 9TB and reports success of the job. Whole disk is selected on both backups.