Webpixels / Customer events not firing

[Addrevenue]

Our app runs on many stores, and it has a custom pixel that subscribes to the checkout_completed event. It works perfectly, but on one single store it doesn't fire. For investigation, I added console logging in the pixel, both outside the subscription and within. I also added subscription to the page_viewed event, Upon further investigation I have found:
- The pixel fires on all pages, but the thank you page (my pixel loading message and page_viewed message is logged to the console).
- On the thank you page, the pixel is not loaded at all. Nothing is logged to the console.
- On all other stores, running this verbose version, pixel loading, page_viewed and checkout_completed it logged).
- Refreshing the thank you page on the problematic store, still doesn't load the pixels.
- Refreshing on all other stores shows pixel loading and page_viewed messages as expected.
- NO pixels are loading on the problematic store. Not only ours.
- No iframes like web-pixel-sandbox.... exists.

Here is how it looks on a working store:

And here is how it looks on the problematic store:

As you can see, no iframes are loading.

The console has warnings (not errors), but they are similar on all stores, only referring to some Google maps deprecated functions, not relevant to this.

The store owner mentions that they are experiences data loss from the facebook pixel, and from what I can see, there is a customer event pixel setup for Facebook as well, but apparently it is not running either.

So this is NOT a case of "certain payment options" not triggering "checkout_completed". And it is not about upsell not triggering "checkout_completed". This is about NONE of the pixels are even started. No iframes opened. No further error messages (like CORS or javascript errors or anything) in the console.

What is happening and how can it be resolved?

Regards,
Peter

[ShopifyDevSup]

Hey @Addrevenue , 

That definitely seems strange that it's happening on a single store and not others. This would be a good one to bring in to our support teams as we would need to look in to details of that specific store. Reach out making sure you're logged in to the store experiencing the issue, and then we can take a look in to that. 

Once you have a resolution, if it turns out to be something that can help other developers, reply here and let us know what it was! 

Hope that helps, 

- Kyle G. 

[Addrevenue]

I actually figured it out, although not completely satisfied with the behaviour. If there are content in the Additional scripts field, none of the web pixels fires on the thank you page. If I do as I'm told on the Checkout settings page, and republish the Thank you page, the Additional scripts field are hidden, and the web pixels starts working again. But the old scripts in additional scripts does not.

I understand the concept of migrating, but since there may be multiple scripts from different services in Additional scripts, this behavior makes it impossible to migrate one script at a time, forcing the store owner to migrate all scripts at once. Which might be difficult or even impossible, if you can't reach the service provider for instructions on how to migrate.

Preferable would of course be to be able to run both web pixels and Additional scripts at once, during the transition period until Additional scripts are completely removed.