Hey everyone,

I've been dealing with a weird issue these past few days that I couldn't quite wrap my head around and was hoping one of you wonderful people might be able to help me out.

We run a full dual integration with Pixel and CAPI for our webshop, sending event data to all advertising platforms we use for our marketing efforts (Meta, Reddit, Pinterest, etc.). We always had the same or slightly higher number of CAPI events compared to Pixel events.

However, about 10 days ago we noticed a sudden and notable drop in our CAPI numbers for almost all events, down to about 1/3 of their previous values. Importantly, the Pixel events have stayed completely stable throughout, which rules out a client-side firing issue as far as I can tell. The only exception to the drop is (luckily) the purchase event, which still behaves correctly and sends ~ the same number of CAPI and Pixel events as before.

I have tried to investigate the root cause and have so far found the following:

1. There were no GTM changes prior to the drop in either the client-side or server-side container that would explain this behavior.
2. As far as I can tell network requests to our server are going out with a "200" status, suggesting delivery is working as intended.
3. Within our SGTM provider Stape, the logs look healthy with no noticeable drop in event volume. The monitoring tab shows a 99.8 to 100% success rate on all outgoing requests to the platform APIs.
4. A bit after the drop started I updated the custom gallery templates by Stape in the SGTM container for Reddit, Facebook and Pinterest to their latest versions in the hopes it would solve the issue, but it didn't.

Interestingly enough the SGTM Preview mode has also started behaving oddly around the same time, only showing the first 3-4 events of a session and then stopping and only picking back up once the purchase event fires and our SPA-Site reloads. From there on the preview mode behaves normally.

However since the Stape logs don´t show a noticeable decline in events I do believe that this is more of a preview-issue than an actual data loss.

Does anybody have an idea what else I could look into or wants to challenge my observations and what I´ve deduced so far?

I'm slowly approaching my wit's end on this one. Any help or pointer would be greatly appreciated!