GraphQL API response data different from GraphiQL API response data

[AlecSwanky]

I have a custom app installed on a Plus store which calls orders and associated data for a certain time period from the API and prints to a .csv file.

However, some orders are not found by the call to the API. I have tested the query with the GraphiQL app installed on the store but the missing orders appear in those calls using the same query and variables. 

Is there any reason why some order objects might not be returned by an API call in an app versus in the GraphiQL app in the store admin?

Query code: 

query (
  $results: Int!,
  $cursor: String,
  $order_window: String
) {
  orders(
	first: $results,
	after: $cursor,
	query: $order_window,
	reverse: true
  ) {
	pageInfo {
	  hasNextPage
	  hasPreviousPage
	}                
	edges {
	  cursor
	  node {
		name
		id
		test
		cancelledAt
		shippingAddress {
		  lastName
		  firstName
		  address1
		  address2
		  city
		  province
		  country
		  zip
		  phone
		}
		displayFinancialStatus
		fullyPaid
		createdAt
		app {
		  name
		}
		nonFulfillableLineItems (first: 25 ) {
		  edges {
			node {
			  id
			  title
			}
		  }
		}
		customer {
		  id
		  firstName
		  lastName
		  email
		  tags
		  ordersCount
		  deliveryComment: metafield(
			namespace: "global"
			key: "order_note"
		  ) {
			value
		  }
		}
		lineItems (
		  first: 25
		) {
		  edges {
			node {
			  id
			  title
			  variantTitle
			}
		  }
		}
	  }
	}
  }
}

Variables: 

{
	"results": 10,
	"cursor": cursor,
	"order_window": "created_at:>#{start_date} AND created_at:<#{end_date}"
}

Thank you