The whole export fails when a contra account is missing from your Pleo accounting settings.
Set up a contra account in Quickbooks. Here's how. If you're using Pocket, please also create a contra account for that. A Pocket contra account has the same requirements as one for card expenses (account type should be "Cash at bank and in hand" and detail type should be "current").
Add the respective contra account(s) to the accounting settings page in Pleo: