Ionic button blank when ion-button used with color attribute

With the latest Ionic (not tested before, this is my first app) for Vue3 Im getting a blank button for ion-button whenever I try to apply a color attribute to the button. I can see the outlines of the button, but the button is blank (white).

This shows blue default primary button:

<ion-page>
    <ion-button
      v-show="show_scan_button"
      @click="SwapComponent('Uploader')"
      expand="block"
      size="large"
    >

This only shows the shadows of the button with white content, no text:

<ion-page>
    <ion-button
      v-show="show_scan_button"
      @click="SwapComponent('Uploader')"
      expand="block"
      size="large"
      color="primary"
    >

Any idea where I might go wrong?

I will bump this up a bit. Any suggestion on how to debug this?

yum, answering my question - did not import

import '@ionic/vue/css/core.css';

in main.ts

A note to myself:

Optionally add

import '@ionic/vue/css/normalize.css';
import '@ionic/vue/css/structure.css';
import '@ionic/vue/css/typography.css';

if something seems weird.