GA4 Measurement Protocol Events Not Appearing (204 Response, Works in Postman)

Hi everyone,

I’m trying to send offline conversion events from HubSpot to GA4 via Zapier using the Measurement Protocol.

Here’s what’s happening:

• When I send the exact same payload via Postman, the event appears correctly in GA4 (Realtime and DebugView).

• When I send it via Zapier, I get a 204 response from https://www.google-analytics.com/mp/collect, but the event never shows up in GA4.

Setup

Zapier App: Google Analytics 4
Action: API Request (Beta)
Method: POST
URL:

https://www.google-analytics.com/mp/collect?measurement_id=G-XXXXXXX&api_secret=YYYYYYYYYYYYYYYYYYYY

Headers:

Content-Type: application/json

Body:

{ "client_id": "1195033321.1751564544", "events": [ { "name": "deal_closed", "params": { "value": 1000, "currency": "USD", "transaction_id": "43658496657", "campaign": "supply-chain-compliance", "source": "google", "medium": "cpc", "debug_mode": 1 } } ] }

Response from Zapier:

Status: 204 No Content

No error, but the event never appears in GA4 Realtime or DebugView.

Notes

• The same payload in Postman (same measurement ID, secret, and client_id) works immediately.

• GA4 property is confirmed active, and other browser-based events are flowing normally.

• I’m not using the built-in GA4 “Send Measurement Event” action, only the API Request (Beta) with the Measurement Protocol endpoint.

Notes

• The same payload in Postman (same measurement ID, secret, and client_id) works immediately.

• GA4 property is confirmed active, and other browser-based events are flowing normally.

• I’m not using the built-in GA4 “Send Measurement Event” action, only the API Request (Beta) with the Measurement Protocol endpoint.

❓Question

Is Zapier possibly stripping or altering the request (e.g., JSON encoding, headers, or redirect behavior)?
Or does the API Request (Beta) action send data through an intermediary service that might affect GA4’s ability to attribute or process it?

Would appreciate any insight or confirmation from others who’ve tried sending GA4 Measurement Protocol hits from Zapier — especially if you’ve successfully gotten them to appear in GA4 Realtime.

Thanks!