1.49 GB "used" on erased USB-C 8TB

Hi everyone
I have searched for an answer to this, but to no avail.
I’ve just bought two new USB-C 8TB drives to use with a MacBook Pro. The first I removed the G-Utilities partition then erased/reformatted. All good, about 850kB used on the drice, happy days.
The second I forgot to delete the G-Utilities partition, but went straight to erase/reformat. Now, no matter what I do in Disk Utility, there is always 1.49GB “used” on that drive.
How do I fully erase that disk in the same way as the first drive? Disk Utility just doesn’t seem able to do it on that drive now, in spite of success on the first drive. I’ve tried erasing and reformatting in Disk Utility, neither have any effect on this seemingly inaccessible “used” portion of the drive.