Max transfer rate is ludicrously high? A3000 SCSI controller is limited to about 10/MB second, IIRC.. So about 0 X 0090FFFF, which is really pushing the metal. That's about 9.5MB. It's nice to think the OS was maximum designed for drives and controllers that can access at 214 MB/S, but they haven't been invented yet, and neither have the processors needed to do that on 68K based Amigas.
Try a complete shut down just after HD-Toolbox preparation, and before you quick format the drives. (don't use slow format).
Sometimes a reboot isn't enough, the new hardware is "clever" and needs to be turned off to reset fully before the Amiga OS can access the drive contents properly. The nearest thing AmigaOS came to removable media was the floppy disk. Everything else needed a custom library and device.
Check your scsi.device version too.
