HA Supervisor won't update

Hi, I’m new to this forum & I would like some help please!
When trying to update HA Supervisor from CLI, I get this error:
“no such image: Package amd64-hassio-supervisor · GitHub

Do you have the recommended disk space - min 32GB?

This may be the problem then, as the system shows that I currently have about 12GB available (out of a total of 22GB) - which is confusing as the mini PC it’s running on has a 120GB SSD.
However, the system has been running perfectly OK for over a year & has updated several times before without issues.
I’m running Home Assistant Supervisor version 2023.12.1 & Home Assistant Core version 2023.4.6 on a pre-built Home Assistant Server Shuttle XS35 PC Computer Atom D510 128GB SSD Supervised (Debian GNU/Linux 11).