Your drive may be formatted in a way that the TV can not recognize(NTFS/EXFAT/ECT).
4TB drives are rather large and some of the normal file systems used for external hardware does not work well with this large drive.
They may have an update for the TV that can fix this issue. I would recommend getting ahold of Samsung to see what file systems and dive sizes the TV supports. They may have just intended it for normal flash drives that tend to not be so large(space wise).