Why is pixel code not working?
Adding pixel code inside of the meta is not necessary and might cause problems.
The pixel code is added by the system for you. You only have to add the Pixel ID and API token as shown on the documents.
Currently, the Add To Cart pixel will only trigger by manually clicking the Add to cart button while the InitiateCheckout currently only triggers when accessing not via Direct checkout.
MMIO will add that functionality soon.