Hi @colinhall
Thanks for your question. I would like to provide some ideas and hope to help you find the root cause of the problem as soon as possible.
The GA4 purchase events you mentioned were not triggered correctly, some orders were not fully displayed, and the URL format of the Thank You page was different. This may be one of the core problems. Usually, GA4 purchase events are triggered according to specific URLs. If the Thank You page URLs of some orders do not match expectations, GA4 may not be able to capture the purchase information correctly. You can check whether there are any third-party plugins or custom codes in Shopify that have changed the URL structure of the Thank You page to ensure that GA4 triggers can cover all possible page URLs.
At the same time, the problem of GA4 cannot be completely ruled out. This may require checking the specific trigger settings or codes. You can ask more professional people.
I hope this can help you.