Event coverage issue

Facebook Conversion API
1

Hi,

We’ve been encountering challenges with event coverage due to a deduplication issue.

Below are the events reported by the pixel versus the server:

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However, the coverage report indicates that deduplication isn’t functioning correctly:

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Both the pixel and DATA tags use the same trigger, event ID variable, and no sequencing, which might be affecting the event ID.

Any thoughts? We’re seeing the same issue with TikTok events and for a few other clients as well, so it seems the problem might lie within the stack (GTM and sGTM by Stape). I’ve tested using transaction_id as event id on purchase events, and that solved the issue for purchase events (shows 90-100% coverage)

2

  1. the coverage report also says there’s no issues detected, so I would take that with a grain of salt.

  2. what do you use for event_id normally?
    1.1. is there tag sequencing in your container?

  3. With TikTok specifically used to have such an issue, spent month debugging with their tech-reps - all to no avail, event_id was present consistently and matched in the event pair.

  4. I don’t expect any issues in the ‘stack’ like you said, you can launch preview mode on both containers and see what data is being pushed, I bet it’s all correct (assuming proper implementation)

3

0.The deduplication report shows that 97% of pixel events and 100% of server events include the event_id value. However, only 61.95% of browser event_id values match the corresponding server event_id values (my interpretation).

  1. I’m using a combination of event name and ID (based on the Unique Event ID template by Stape). For example: page_view_1733916122369_173391563723915672.
    1.1. I’ve removed tag sequencing for FB and DATA tags, however, GA4 tags still use sequencing.
  2. Exactly. I confirm that in preview mode, the event_id values both for pixel and server appear correct, so I suspect there might be race condition scenarios where retrieving the event_id is slightly delayed.
4

Your problem is most likely in using the tag sequencing option. This affects the event id that is used in the tag.
You can check this by running container previews and making sure the event_id in the events is the same.
In general, I recommend using tag sequencing as a last resort when there are no other options to make the required function (although this can usually be solved by using a trigger group).