Why can't I find my property in Data Query?

When you create a property in your Data Model, and it has been validated, it must appear in the other Piano Analytics interfaces. 

Let's take an example with a "src_utm_id" property we have created:

On Data Query, we see that our property doesn't appear when we search for it. To see it appear, simply click on the settings icon and check the "Search in inactive items" box:

You will then be able to see your property in the suggestions and select it.
 
The fact that we cannot see the property directly when we search for it stems from the fact that no data has yet been collected on it: