Silent Failure of Proxmox Backup

[presarioch]

Has no idea why my backup failed with no reason. The log was saying that the backup job finished successfully, but the archive file size was 0 KB. In conclusion, the backup was actually unsuccessful as there's no backup file in the file system. Here is the log:

INFO: starting new backup job: vzdump 1010 --mailnotification failure --mode snapshot --compress zstd --node pve1 --all 0 --quiet 1 --storage nasstore2
INFO: Starting Backup of VM 1010 (qemu)
INFO: Backup started at 2021-07-21 05:36:02
INFO: status = running
INFO: VM Name: somebody-win10
INFO: include disk 'scsi0' 'nasstore1:1010/vm-1010-disk-0.raw' 100G
INFO: backup mode: snapshot
INFO: ionice priority: 7
INFO: creating vzdump archive '/store/nasstore2/dump/vzdump-qemu-1010-2021_07_21-05_36_01.vma.zst'
INFO: started backup task 'f2cdd8bf-5c02-43de-b34f-f732a2acb41e'
INFO: resuming VM again
INFO: 0% (50.8 MiB of 100.0 GiB) in 3s, read: 16.9 MiB/s, write: 14.8 MiB/s
INFO: 1% (1.0 GiB of 100.0 GiB) in 1m 53s, read: 8.9 MiB/s, write: 8.7 MiB/s
PROGRESS SKIPPED for shortening the post.
INFO: 99% (99.0 GiB of 100.0 GiB) in 1h 57m 4s, read: 20.0 MiB/s, write: 20.0 MiB/s
INFO: 100% (100.0 GiB of 100.0 GiB) in 1h 58m 11s, read: 15.2 MiB/s, write: 14.4 MiB/s
INFO: backup is sparse: 1.59 GiB (1%) total zero data
INFO: transferred 100.00 GiB in 7091 seconds (14.4 MiB/s)
INFO: archive file size: 0KB
INFO: Finished Backup of VM 1010 (01:58:15)
INFO: Backup finished at 2021-07-21 07:34:16
INFO: Backup job finished successfully
TASK OK

Here is some detail of the proxmox:
Version: 6.4-13
CPU: i7-3770
Memory: 32GB
nasstore1 is NFS mounted while nasstore2 is CIFS mounted.


Some more information for what I've tried:

• Tried both nasstore1 and nasstore2 were readable and writable.
• The mount point is already 755. 777 is also tried but again unsuccessful.
• Tried manually running the command "vzdump 1010 --mailnotification failure --mode snapshot --compress zstd --node pve1 --all 0 --quiet 1 --storage" also resulted at the same.
• Tried a lot several times already.
• Tried different compression method, lzo, gzip, zst, also resulting the same.

So frustrating... Thanks for the help in advance!