BigCommerce has recently made changes to support upgraded Facebook Pixel tracking for the new Conversions API.
Without this upgrade, you may be experiencing discrepancies in data & conversions reporting by Facebook which is sent to not only BigCommerce but also platforms like Sales & Orders as well.
To upgrade your connection to Facebook Pixel, log into your BigCommerce store and go to Advanced Settings > Data Solutions > Facebook Pixel > and click Upgrade connection.
Once you’ve completed the upgrade steps data will immediately be sent via the Conversions API in addition to the javascript pixel. No development work is required on your part.