So I took the enclosure apart and took the drive out, grabbed a sata cable and slapped it into my computer. Problem is disk manager shows 2 equally sized partitions and I can't do anything to them.
If you are using MBR as the partition type you won't be able to create a 4TB partition. Try converting to a GPT partition table and you should be good to go.
If you are using MBR as the partition type you won't be able to create a 4TB partition. Try converting to a GPT partition table and you should be good to go.