The email has no PDF attachment
Check that the file is visible in the Invoice PDF metabox and that the email is enabled under Inference Works → Order invoices. Only Completed order is selected by default. Upload the document before changing the status or sending an email manually; an earlier email cannot be updated afterwards.
No Invoice button in My Account
Check Show invoice in My Account and confirm that a PDF exists on the correct order. Without a file, the button is intentionally hidden. Downloads require permission: the logged-in order owner, a shop manager or a valid guest order key.
The status changed despite blocking
Blocking applies to manual changes. Checkout, REST, WP-CLI and cron always use warning mode. Check the order notes and how the change was triggered; see warnings and blocking.
Upload or download fails
Check that the file is a PDF within both the configured size limit and server upload limits. Check write access to uploads. For downloads, verify that the file still exists and the user has permission. Invoices are stored separately, outside the media library.
Nginx and direct file URLs
Nginx does not process .htaccess. Your administrator must deny public access to iwoia-invoices and the legacy oia-invoices. Download through the plugin’s permission-checked endpoint. Random filenames do not replace server access restrictions.
Upgrading, old invoices and uninstalling
Deactivate the former plugin with its old slug before activating 1.2.0. Older PDFs remain in oia-invoices; do not move them manually or uninstall the old copy with data cleanup enabled. Deleting files and settings on uninstall is disabled by default.
If the problem persists, contact support with WordPress, WooCommerce, PHP and plugin versions, classic/HPOS order storage, the selected email and reproduction steps. Do not attach invoices or customer data to a public issue.