Meta Pixel on Multiple domains Not Working - Only works on one domain

[alekszent]

Hello everyone, 
Perhaps discussed solution to my problem could be helpful to others.

Our issue in a nutshell: Meta Pixel is only working on one of three domains.

And it's not even working on a primary domain (.de) but market/subdomain (.com). The installation was done through Facebook & Instagram Shopify App. When done manually through adding Pixel code to theme.liquid, it works on all 3 domains but then the checkout pixel tracking is not working (but when installed through the shopify Meta app it tracks checkout but only on 1 domain).

We have added additional domains to expand internationally. Currently we have the following domains:

- .de - Primary domain

- .com – Market domain /separate/subdomain

- .fr – Market domain /separate/subdomain

So it's odd that the pixel actually works on the market domain and not primary domain.

Any ideas/recommendations how to have the Meta Pixel work across all 3 domains including Checkout?

Is there something to be done on the Meta Sources side to include these other domains?

Or different way of initialization of Facebook & Instagram app? Or adding pixel through Customer Events section?
We're using Shopify plan (not plus/advanced). 

Thank you for any insights.