Failed to retrieve shipping label refund status

It sounds to me like it might be a problem specifically related to the status of your payments for shipping labels, possibly involving refunds. It could also be a problem based on an account or database change. If you haven’t already, you might check the WPAdmin > WooCommerce > Settings > Shipping > WooCommerce Shipping section in your dashboard and verify the credit card on file there is the correct one and that it is not having any problems with new charges or recent refunds.

When you say you downgraded the plugin, do you mean you installed an older version of the plugin (do you know which version?) or do you mean that you deleted the plugin and then re-installed it? Are you using the latest version of the plugin now?

To get further help, I would recommend contacting the support team directly at https://woocommerce.com/my-account/create-a-ticket/?form=ticket and include a copy of the status report from WP Admin > WooCommerce > Settings > Status and, if possible, a screenshot of the error (including a view of the console errors if you can get that) and as much information as possible that you can provide about any recent changes you’ve made to your site or any refund requests you have made for shipping labels. For example, have you made any recent changes to the database for your site or did you move from a staging server to a live server recently? Did you request one shipping label refund and it went through but you continue to receive an error about that refund? Or did you make several refund requests recently by chance? Did you request a refund but then change the card you’re using for shipping labels afterward? Anything like that would be helpful for them to know.