GTM Consent Mode Debugging with Tag Assistant

[buffalom]

I built a custom cookie banner and am trying to make it work with GTM Consent Mode.

In nuxt.config.ts, I've got the following config:

scripts: {
  registry: {
    googleTagManager: {
      id: '...',
      trigger: 'onNuxtReady',
      bundle: false, // Required to make Tag Assistant (Preview Mode) work
      defaultConsent: {
        // https://developers.google.com/tag-platform/tag-manager/templates/consent-apis
        ad_storage: 'denied',
        ad_user_data: 'denied',
        ad_personalization: 'denied',
        analytics_storage: 'denied', // Start denied, update when analytics accepted through useCookieConsent
        functionality_storage: 'granted', // Always granted
        personalization_storage: 'denied',
        security_storage: 'granted', // Always granted
      },
    },
  },
},

$development: {
  scripts: {
    registry: {
      googleTagManager: 'mock',
    },
  },
},

In my app.vue, I've got something along the lines of:

// Initialize cookie consent management
const gtm = useScriptGoogleTagManager()

gtm.onLoaded(() => {
  console.log('Google Tag Manager loaded, initializing consent status')
  gtm.consent?.update({
    analytics_storage: 'denied', // Default to denied until user gives consent
  })
})

onMounted(() => {
  setTimeout(() => {
    console.log('Updating consent status to granted for analytics_storage')
    gtm.consent?.update({
      analytics_storage: 'granted',
    })
  }, 2000)
})

I've done this in an attempt to debug the consent mode. In reality, I have a composable (useCookieConsent()) that would track cookie banner consent in a reactive which I watch on for changes, which in turn will to the consent update.

For some reason my tags are always loaded even initially, when cookies should be rejected. This is why I am trying to debug it using the Tag Assistant. However, the Tag Assistant never shows anything related to consent as seen in the following screenshot. Neither the default consent nor the consent update appear. As I understand it, it should display the configured consent in the consent (Einwilligung) tab, as well as show a consent event on the left.

Any ideas what I might be doing wrong?