NRQL alert not firing

I have an NRQL alert configured against Synthetics failures, and I can’t figure out why it isn’t firing. It’s intended to fire when three or more test locations report failure and this happens for at least two minutes.

SELECT count(*) >= 3 FROM SyntheticCheck WHERE monitorName = '<my monitorname>' and result = 'FAILED'

The preview seems to show it clearly failing.

Built-in alerts on synthetics seem to work fine (a multi-location failure, for example).

Hello! We ran this NrAiSignal query on your condition:
FROM NrAiSignal SELECT error WHERE conditionId = 23022523 and found that
SELECT count(*) >= 3 FROM SyntheticCheck is returning a boolean, throwing the error:
Non numeric (boolean) value cannot be evaluated.
I’m not sure why this operator, >= 3, is in the SELECT clause, but it seems to be preventing the condition from opening an incident. If you want the condition to open at a count equal or greater than 3, try taking care of this in the alert threshold instead.