scatter could not move more than one files (not directory)

[shuosiw]

I want to move 2 file from disk2 to disk4

but in PLAN it said that:

PLANNING: Planning started
PLANNING: Scanning SCATTER/1 on /mnt/disk2
PLANNING: Checking issues ...
PLANNING: Getting items ...
PLANNING: Scanning SCATTER/2 on /mnt/disk2
PLANNING: Checking issues ...
PLANNING: Getting items ...
PLANNING: Found /mnt/disk2/SCATTER/1 (4.00 B)
PLANNING: Found /mnt/disk2/SCATTER/2 (4.00 B)
PLANNING: Trying to allocate items to disk4 ...
PLANNING: Ended: Jun 3, 2022 14:23:52
PLANNING: Elapsed: 6ms
PLANNING: The following items will not be transferred, because there's not enough space in the target disks:
PLANNING: SCATTER/2
PLANNING: Planning Finished

in actually, disk4 has 13.4TB free space. there's ENOUGH SPACE in the target disks.