So that looks as if your NTFS should support sparse files.
Are you running any antivirus? I wonder if that is interfering?
@asdffdsa can you think of any reason why sparse files wouldn't work on NTFS with Windows 7?
The upcoming --vfs-cache-mode full relies on sparse files so it would be annoying if they aren't supported properly by Windows 7.
Is there anything else unusual about your system @attem ?