WD20EARS 2TB HDD Reports Only 1TB

Hi Folks. (Just joined; my first post.)
I have searched on “WDEARS20” on this forum but can’t find a thread with exactly my problem.

The label on my HDD shows it is supposed to be a 2TB HDD, but I cannot get any more than 1TB, either with Win 10 tools or with any other diagnostic tool - Disk Sentinel and Crystal Disk. Apart from that it works well enough.

I use this drive in a Volans Drive Dock, via a USB3 connection to an Asus Laptop. I have also tried it in an Xsonic USB2 dock on the same laptop, getting the same result. I have checked the specs of the docks and they’re supposed to read more than 1TB.

An image of the setup is attached.

Thanks for any help.