berwhale, what controller cards are you using?
I've just got a T20, and want to move over my 4 hard drives from my N54L, and add a couple more but it seems the controller card I got pexsat32 and it (https://www.startech.com/uk/Cards-Adapters/HDD-Controllers/SATA-Cards/2-Port-PCI-Express-SATA-6-Gbps-Controller-Card~PEXSAT32) doesn't seem to be compatible with DSM 5.2 as I can't see any hard drives in DSM when it's added to pass-through.