I got this message working with a new site and am wondering if tailwind is even compatible with wordpress. Is this postCss a plugin for Wordpress? Seems unnecessarily complicated.
Was your tw css file replaced, or your tw classes present differently, or both?
When you turn on design panel, all default tw colors are used and will show up there. You can change those default values to your custom palette. You can also add additional ones like primary, secondary etc (so that you can use text-primary-500).