6TB HDD Transfer from Old Enclosure to New One, Not Recognized

[Acid Blue]

Hi guys! I transferred my files to a new HDD from my old 6TB (6TB WD60EFRX Red), so I decided to move the old drive into a multidock enclosure. The first to fresh drives ran fine and was formatted easily. I transferred the old 6TB to the multidock enclosure, but it wasn't recognized. In disk management it appears as partitioned (~2TB and ~4TB). The 2TB partition appears is indicated as GPT and the 4TB as unallocated. But when I ran diskpart, it appears as a 6TB drive that is not GPT. But when I try to convert the drive to GPT via disk part, it said that its read only. Also ran it in AOMEI disk partition assistant, it also indicates the drive as GPT, but I can't format or have it repartitioned. The data on the drive is already backed up in the new drives so, I don't mind wiping the 6TB. Any idea how to resolve this?

Update: The drive still works when plugged into the old enclosure, but not when moved to another

 

[Hlsgsz]

The diskpart clean command will help you:
diskpart
list disk
select disk x(where x is the drive in case)
clean
convert gpt
exit

EDIT: you want to keep using GPT, as MBR has an upper 4TB partition size limit and it doesn't make sense to partition large media storage drives.

 

[Acid Blue]

Thanks Hlsgsz, that worked

 

[Hlsgsz]

No prob. You're welcome!