While QA'ing your GTM Suite Installation, have you found that it's not firing on a few pages? If so, here are a few things to double check:
Or, if you have completely custom pages, does this exist on those page templates?
If not, then copy this into your template just above the closing </body> tag:
You can test by searching in your theme files here:
If you do have something besides product.liquid, then these need to be added as an "or" condition in our elevar-body.liquid snippet:
Questions? Let us know!