This can happen when moving from/to RAID controllers that don't use the standard partition, you should be able to fix it by rebuilding all the disks one at a time, since Unraid will recreate the partition, stop array, unassign one of those disks, start array, the emulated disk should mount and show the correct data, if yes, and only if yes, reassign the disk to rebuild on top, then repeat for the remaining disks.