sessionKeyEventRate fails when referencing a specific key event in Looker Studio, while the overall metric works

Looker Q&A Looker
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Hi everyone,

I’ve encountered an issue when using GA4 key event metrics in Looker Studio.

Here’s what’s happening:

  • The overall metric Session key event rate works perfectly in Looker Studio.

  • However, when I try to use sessionKeyEventRate(Event Name) for any specific key event, Looker Studio throws an error.

  • All key events are configured correctly and appear as conversions in GA4.

  • I can see conversion counts in GA4 reports for each event, so the tracking itself works fine.

  • The events are sent from Google Tag Manager using the same GA4 configuration tag — no custom “Create event” rules inside GA4.

Troubleshooting so far:

  1. Event names (aliases) match exactly between GA4 and Looker Studio.

  2. Each event is marked as a key event in GA4.

  3. The Looker Studio data source schema was refreshed several times.

  4. Other GA4 metrics (Event count, Conversions, Sessions) work normally.

  5. The issue occurs only when referencing a specific key event, not with the overall sessionKeyEventRate.

  6. To rule out configuration issues, I created a new GA4 property and added a new test tag in the same Google Tag Manager container, configured with the same triggers and parameters as the original one.
    → In the new property, the sessionKeyEventRate for that event worked correctly in Looker Studio.
    → However, in the original GA4 property, the same type of event still fails to return any data or throws an error in Looker Studio.

Observed behavior:

  • In GA4 UI, conversions and key events are counted correctly.

  • In Looker Studio, the overall Session key event rate metric works fine.

  • But when referencing a particular key event (e.g. sessionKeyEventRate(Start with Jira)), Looker Studio fails to display any data or returns an error.

When I try to recreate the rate manually using

SUM(Event count) / SUM(Sessions)

with a filter on eventName, it produces technically valid results, but the ratio becomes incorrect because the filter applies to both numerator and denominator — resulting in a constant value of 1.

Hypothesis:

The event itself was originally created in GA4, not migrated from Universal Analytics.
However, key events as a separate concept were introduced later, after this event already existed in the property.

My current hypothesis is that there might be a mismatch in how GA4 internally maps the parameters of “older” events to the new key event structure — resulting in missing or incompatible data fields for sessionKeyEventRate in the API response.

I found a few similar discussions suggesting that key event conversion rate may be broken for certain events, such as this one on Google Developer Forum, but re-fetching or refreshing the data didn’t solve it in my case.

Question:

  • Has anyone else experienced this — where sessionKeyEventRate(Event Name) fails, even though the event is correctly set as a key event in GA4?

  • Could this be related to how GA4 retrofits older events into the new “key event” model?

  • Any known workaround or clarification from Google regarding this behavior?

Environment:

  • GA4 property (standard web stream)

  • Events sent via Google Tag Manager (same configuration tag)

  • Looker Studio directly connected to GA4 (no BigQuery)

Thanks in advance for any insights or confirmation from the Google team or community!