Missing Some Deduplication Parameters

I’ve just done some testing of this on my own test site here: https://wctesting.tk/product/beanie-with-logo/. I used this plugin: https://github.com/WillBrubaker/maybe-route-request-through-moesif to capture the request that was sent to the FaceBook conversions API and I used the Facebook Pixel Helper Chrome browser extension to view the data that is sent using the FaceBook Pixel. With all of that in place, I added an item to my cart. The pixel event shows that the event_id parameter is populated:

Likewise, the request that was sent to the API also contains a value in the event_id parameter:

I also had a look at the issue tracker here: https://github.com/facebookincubator/facebook-for-woocommerce/issues for any reports of this type of behavior caused by the Facebook for WooCommerce but I was unable to find any. This leads me to believe that this is caused by something external to WooCommerce or Facebook for WooCommerce. If you are able to provide the exact steps that can be taken to reproduce this behavior under the following conditions:

1. An unmodified, default WordPress theme such as Twenty Twenty or Storefront active.
2. No other plugins except for WooCommerce and Facebook for WooCommerce active.

Please do provide those steps and we can take a closer look.
We do understand that placing a site under those conditions may be disruptive. Many people maintain a staging copy of their site for exactly this purpose. That way, testing and troubleshooting can be done on the staging copy without disrupting the operation of the live site. If your host does not provide an easy way to set up a staging site, you might want to use something like the WP Staging plugin for this purpose.

To make sure we stay on topic (troubleshooting), this thread is considered resolved. To close the loops from above: @ngsoes, if you need further assistance, please open up a new ticket as @danielinhou had requested.

Thanks!