Editing an Associated Merchant on an Order and cancelling removes value in the field.

When you edit an Order and try to change the associated merchant field then click cancel, the associated merchant field is now blank. You don't get the warning about unsaved changes. If you click cancel again, you get the unsaved changes warning. If you choose to lose the changes, the order will revert to the saved values. If you keep the changes and stay on the order page, you can continue editing but the system things you cleared the associated merchant field.

If you edit the associated merchant field and change it to a valid associated merchant, cancel works as expected. This is only an issue when you enter an invalid/non-existent merchant while editing and click cancel. I used a random string of characters in the merchant field to reproduce this.