Hi,

It's commendable that you successfully resolved the issue of generating XML files for foreign sales invoices in Odoo 17 for the Italian tax service (SDI). Your solution, which involved deleting the automatically proposed billing document and the associated PDF, effectively reset the invoice's internal status. This likely occurred because Odoo's Italian localization module, with its specific state management for electronic invoicing, might have internally marked the invoice as being in a state where further XML generation was either considered complete or not applicable, thus deactivating the XML checkbox.

For future similar challenges, especially with electronic invoicing or other localization features, it's advisable to always check the document's "State" as certain states can restrict modifications. Additionally, understanding the unique workflows and validations inherent in localization-specific modules, and being aware of how Odoo's automatic document generation processes might interact with manual actions, can help in troubleshooting. For complex or recurring issues, consulting an Odoo Partner specializing in Italian localization or contacting Odoo Support directly remains the most reliable approach.