Since usage-based add-ons are billed at the end of the billing cycle, they are not included in the Revenue Recognition export. You can confirm this by seeing that there is no Revenue recognition method option when creating the add-on on a Plan. Fixed-price add-ons will show a Revenue recognition option.
For example, here are the editing fields available for a usage-based add-on, and you can see there is no drop down menu for Rev Rec method:
Now, in this example, you can see that a fixed-price add-on does have a drop down menu for Rev Rec:
I hope this helps. If you have any other questions on this topic, please contact our support team at: Support@recurly.com