As noted in the documentation, some attributes are optional, on a Pledge for example:
// optional properties
"total_historical_amount_cents": <int>
"is_paused": <bool>
"has_shipping_address": <bool>
You must request these attributes explicitly to have them included in the response. However, a very important caveat is that when you explicitly request any attribute you must explicitly request every attribute you wish to be included. Therefore, if you would like to have access to is_paused with the default data you’ll need to explicitly request is_paused, created_at, amount_cents, declined_since, has_shipping_address etc.
You can find an explanation of how to request optional data in the documentation here: https://docs.patreon.com/#requesting-specific-data
My library builds a request URL containing each property of the entity, you can see how it does that here: https://github.com/1f991/patreon-php/blob/master/src/Patreon/Resources/Resource.php#L128
Let me know if you need any other information 