Old MBLD Drive in USB Not Showing Data

I have just upgraded the capacity of my MBLD and have a working empty RAID1 array. Fantastic.

But I need to copy the old data onto the new drives. I have been informed all I need to do is plug the old drive into the MBLD USB port and use SSH to copy the DataVolume across - that would be fine, but when I plug an old drive in, it shows as 0 capacity and 0 usage. I know there is data on the drive as I have been using it and various partition tools (on windows) show it as 1,8TB full.

Interestingly, there is no /mnt directory on the MBLD, there used to be, I don’t know if this is since a firmware upgrade.

Can anyone tell me how I mount this drive either on the MBLD via USB or in Windows 10 (much slower but whatever works)?

DiskInternals Linux Reader detects the drive but “can’t open” it.
EaseUS Partition Master shows the drive as Unformatted, capacity 1.8TB, in use 1.8TB type: primary

(it’s a 2TB drive)

UPDATE:
If I plug the 2TB old MBLD hard drive into the PC internally using SATA, I get the full 5 partitions of the table, Unallocated, Other and 3x ext3. All are GPT
But I still can’t access the data in windows

UPDATE 2:
Using Ext2VolumeManager, I have assigned a drive letter to the ext4 partition (which contains the data) and now have access via Windows Explorer. I can now copy files from this drive to the MBLD on the network.

While this works. It’s going to be slow (2 hours for 15GB), so any input on pugging the old HDD into the USB on the MBLD would be greatly appreciated

UPDATE 3;
ex2VolumeManager crashes windows so I cant use that to copy the data.
I believe the problem stems from the old drive being connected to the new MBLD using a powered SATA->USB device

I am most glad you have been able to find a way to access your data. Hopefully you’ll be able to successfully retrieve and transfer it into your NAS.