I have a 12TB SATA drive, using a powered adaptor that I want to connect to the USB port. The drive has two 6TB HFS+ partitions (GPT partition table). When I plug it in, the drive does not even spin up, and Roku does not see any connected devices (let alone read the files on it). The main barriers I've found to USB not working are disk format (HFS+ is supported) and power (the adaptor is powered). I don't think the partition size is a problem as I've read accounts of people using 8TB drives without any issues.
I have also tried a 512GB laptop drive in an (unpowered) enclosure, HFS+ formatted, also using GPT. The Roku does see this device and I can browse files.
Anyone have ideas why the 12TB drive isn't being picked up by the Roku?