Hi Vicko1, did you use the “Google Tag Assistant Legacy Chrome extension” ?
https://chrome.google.com/webstore/detail/tag-assistant-legacy-by-g/kejbdjndbnbjgmefkgdddjlbokphdefk
Topic summary
Developers are encountering issues when implementing Google Tag Manager (GTM) through Shopify’s Custom Pixel feature in the Customer Events admin. The core problem: GTM does not properly initialize when included as a custom pixel, and dataLayer events pushed from custom pixels don’t appear in GTM’s preview/debug tools.
Root cause identified:
The custom pixel code runs in a sandboxed iframe environment, preventing standard GTM debugging methods from working. Events fire and appear in console.log outputs, but aren’t visible in GTM’s preview mode or the legacy Tag Assistant extension.
Workarounds suggested:
- Use browser network tab to inspect GTM requests and analytics payloads
- Implement server-side GTM containers for better debugging capabilities
- Test in production or separate test stores with published GTM configurations
- Use DataLayer Checker Plus Chrome extension
- Rely on console.log statements and Google Analytics Real-Time reports for verification
Key frustrations:
- Cannot validate tags before publishing due to sandbox limitations
- Must test with live/published GTM setups rather than draft configurations
- Checkout tracking particularly difficult to debug
- Some users report cross-domain policy errors
Status: No official fix from Shopify. Multiple users confirm checkout_completed and other standard events work when properly implemented, despite debugging limitations. The discussion remains open with ongoing troubleshooting.