Flatline with no matches

Hi, I'm clearly missing something simple but:

my_rule.yaml

type: flatline
index: index-*
threshold: 1
timeframe:
  hours: 24
use_count_query: true
doc_type: doc
filter:
- query:
    query_string:
      query: "application:\"nonsense\""

I would expect that: elastalert-test-rule my_rule.yaml would say something like "An abnormally low number of events .." because obviously there are no events with field and value "nonsense" and there will never be. However, if I change timeframe to hours:1, strangely it hits the rule and says "An abnormally low ...". To make sure I created that original rule and left for days, but still no alerts...