Shopify not notifying customers about refunds

Hello,

When I test the “Refund functionality” I get a email confirmation for the refund. The order timeline also shows:

You sent a refund notification email to Firstname Lastname (firstnamelastname@gmail.com)

However I just refunded 2 customers and made sure “Send a notification to the customer” is checked.

However the customers did not receive a notification. The time line does show that the order was refunded but it does not say anything about the notification like it did for my test order.

same issue