I’d only got as far as choosing 15 colors, and making them larger blocks, in order to screenshot the blocks, then bring the screenshot in to manually create a palette from. With 64 colours that would take you a very long time! Might it be that there are other dockers on that side of the UI, and there isn’t space to show the 64? Total guesswork here, lol, as I’m not very tech about things.
Looking at the palette docker notes, I can’t see that e.g. a png/screenshot can be imported: https://docs.krita.org/en/reference_manual/dockers/palette_docker.html
Unfortunately I can’t find any information about the ‘colours from image’ in the manual, but hopefully someone who knows this feature better can help with why it isn’t showing enough colours and any possible way to save the colours.
This was where I found out about this feature: https://krita-artists.org/t/colors-from-image/6341