Deactivate Other Plugins
Temporarily deactivate all other plugins except WooCommerce and Checkout Field Editor. This helps identify if another plugin is causing a conflict. If the issue disappears with all other plugins deactivated, reactivate them one by one to pinpoint the conflicting plugin.
WooCommerce Blocks
If you’re using the new WooCommerce Blocks editor for the checkout page, the Checkout Field Editor might not work as intended. Consider switching back to the classic checkout editor (WooCommerce > Settings > Advanced > Checkout Blocks).