Hi Pepe, thank you for the support.
After several searches I found where this is going wrong.
The problem seems to come from Polylang For WooCommerce, the missing order is made by an English account on the store and this seems to block the order email sending process and prevents the display of this order. If I switch it to Fr it is displayed.
My admin language menu is set to all languages, even switching to In it doesn’t appear.
I am in contact with Polylang support.
Regards.
Jean