can't change meta or title with vue-meta 3 in Vue/ClI setup

Question

i have a problem with the vue-meta-3 plugin with vue3/cli

following basic configuration:

"dependencies": { .... "vue": "^3.0.0", "vue-meta": "^3.0.0-alpha.7", "vue router": "^4.1.2", "vue3-qr-reader": "^1.0.0", "vue3-touch-events": "^4.1.0", "vuex": "^4.0.2" }

  "devDependencies": {
     "@vue/cli-plugin-babel": "~4.5.15",
     "@vue/cli-plugin-eslint": "~4.5.15",
     "@vue/cli-service": "~4.5.15",
     "babel-eslint": "^10.1.0",
     "eslint": "^6.7.2",
     "eslint-plugin-vue": "^7.0.0",
     "sass": "^1.53.0",
     "sass-loader": "^10.2.0",
     "vue-cli-plugin-tailwind": "~3.0.0"
   },

in main.js

import { createMetaManager } from 'vue-meta'
app.use(createMetaManager())


import { useMeta } from 'vue-meta'

export default {
  
   name: 'app',

setup(){
     const router = useRouter();
     const route = useRoute();
     const store = useStore();
   ...

     useMeta({
       title: 'XXX',
       htmlAttrs: { lang: 'de', amp: true }
     })

unfortunately I can't see any output for the title, however there is no error...