Shopify refunds showing all in one day

Hi

We have imported our Customer and Order data across from Shopify to WooCommerce this week.

Strangely, when the orders import completed, all refunded orders that were processed via Shopify were triggered all at once and and 530 customers received an email notifying them that a refund has been processed. This also reflected in Wednesday’s WooCommerce sales report, as the $6,362.04 worth of refunds (all from the Shopify store) was deducted all in one day. Screenshot of this is https://snipboard.io/RHBou5.jpg

All other order data i.e. completed sales is spread evenly throughout the sales report, so you can see a correct figure of sales for each month. But the refund amounts are not spread throughout the history and just appear all in one day – when the import took place.

Is there any explanation for this please?

Thank you