Webpixel extension not firing on some stores

I have a shopify app that uses webpixels extension but for some stores but working as expected for most of the stores. Can anyone help me what can be the issue?

Are there any commonalities for stores where the pixels are not working as expected?

Hi,Liam thanks for your reply,

I am not sure if there is anything common in stores where pixels are not working as expected. I am providing you the urls of stores that have issue.You can check the stores that might help you to figureout the problem

Hope You will find some thing that will be helpful for shopify app developers community
Here are the links:
https://prodottiquantici.com/
https://shopzetu.com/