diff --git a/htdocs/ai/tools/crud_objects.class.php b/htdocs/ai/tools/crud_objects.class.php
index 9b5f25e1fda..61933736148 100644
--- a/htdocs/ai/tools/crud_objects.class.php
+++ b/htdocs/ai/tools/crud_objects.class.php
@@ -621,7 +621,14 @@ If user says 'order' without any qualifier, they mean a SALES ORDER - use this t
 			$res = $object->addline($desc, $price, $qty, $vat, 0, 0, $fkProduct, $discount, 'HT', 0, 0, $prodType);
 		} elseif ($docType === 'supplier_invoice') {
 			/** @var FactureFournisseur $object */
-			$res = $object->addline($desc, $price, $qty, $vat, 0, 0, $fkProduct, $discount, 0, 0, '', 0, 'HT', 0, $prodType);
+			// IMPORTANT: FactureFournisseur::addline() does NOT share the same signature
+			// as Facture::addline(). Its parameter order is:
+			//   ($desc, $pu, $txtva, $txlocaltax1, $txlocaltax2, $qty, $fk_product, $remise_percent, ...)
+			// i.e. $qty is in position 6, not 3 (unlike customer Facture / Commande / Propal).
+			// The previous call passed our $qty as $txtva (-> a 1% VAT rate) and our $vat
+			// as $txlocaltax1, and position 6 ended up being a hardcoded 0 -> a line was
+			// inserted with qty=0, which Dolibarr silently dropped from the visible totals.
+			$res = $object->addline($desc, $price, $vat, 0, 0, $qty, $fkProduct, $discount, '', '', 0, 0, 'HT', $prodType);
 		} elseif ($docType === 'supplier_order') {
 			/** @var CommandeFournisseur $object */
 			$res = $object->addline($desc, $price, $qty, $vat, 0, 0, $fkProduct, $discount, 0, 0, 'HT', 0, '', '', $prodType);