maxAge setting in DatadogMetric not working

[asierraq]

I have a DatadogMetric manifest like the following:

apiVersion: datadoghq.com/v1alpha1
kind: DatadogMetric
metadata:
  name: metric
spec:
  query: (sum:metric1{name:name1} by {name}.as_count().rollup(sum, 300) + sum:metric2{name:name1} by {name}.as_count().rollup(sum, 300)) * avg:metric3{name:name1} by {name}.rollup(sum, 300) / 3600

When I apply it and use it in an HPA, I get the following error:

Query returned outdated result, check MaxAge setting, query: (sum:metric1{name:name1} by {name}.as_count().rollup(sum, 300) + sum:metric2{name:name1} by {name}.as_count().rollup(sum, 300)) * avg:metric3{name:name1} by {name}.rollup(sum, 300) / 3600

Then I added the maxAge: "300" setting (to my surprise it is a string setting and not an integer) and now I'm not getting any events in the DatadogMetric.

Do you know what could be wrong with this setting?