The reason why the colour swatches don’t appear to have any colour is because the CSS variables aren’t defined on the Gutenberg page. If you set a colour, then view the frontend, it’ll look fine.
To fix this, we need to include the CSS variables in the editor.
In Sage, there is an editor entrypoint set up for this purpose. We can include the CSS variables in ./resources/styles/editor.css and the swatches will then have the correct colour, providing that the bundle is enqueued on enqueue_block_editor_assets - like it is in Sage out of the box.
You were right, all colors are working now. Thank you very much for your help
Maybe just one more thing. We use .useTailwindColors() in bud config which causes that only Tailwind colors are visible in Gutenberg. Is it somehow possible to show custom color picker as well? I didn’t find anything in the documentation.