I have this problem, which I have never done before, cause this particular problem lies with some old tech, I've searched the web about this but no methods work such as booting into gparted.
I have two drives that have encryption from toshiba, my investigation resulted into thinking that the drives are married with the hardware of the laptop that it derived in. If you connect it to anything other than the laptop that it's married too it will hide the partitions and your out of luck, they both function fine when i boot them in the laptop but another problem arises when no one knows the password. The story of the laptop from a friends parents request to gain access back into it, I didn't ask questions since they said they didn't care for the data on it, they just want to use it again.
Here are the hardware specs: (Pictures are low quality due to crappy interwebs)
And yes, since this is really old, it has no warranty so I'm all ears at this point.