In order to include this field in a query or report, we must first enable the field
  1. Click Management
  2. Click User Defined Fields
  3. Select the category where you store the field
  4. Click the Show Disabled Fields button below the Tasks menu (if the disabled fields are already displayed, please skip to the next step)
  5. Click the Enabled button below the name of the User Defined Field that you'd like to include in the query or report
  6. Click Save and View all Categories

Then, we'll create the Query and Report using the now enabled User Defined Field. Once you've created the query and report, we'll disable the field again using the steps available at How to disable a User Defined Field. The query and report will still contain the disabled field.