Product position is reset to zero after product import/update

[JoostWan]

When we run the import to update qty of products, the position of that product will be reset to zero in the category.

We use $this->setBehavior(Import::BEHAVIOR_ADD_UPDATE);

   $productStock[] = [
                        'sku' => $row[1],
                        'use_config_manage_stock' => 0,
                        'use_config_backorders' => 0,
                        'manage_stock' => 1,
                        'backorders' => 1,
                        'is_in_stock' => $stockStatus,
                        'levertijd' => $row[7],
                        'qty' => $qty
                    ];

I tested it also with the normal import function in the backend. Then the product position in the category will be the same and not reset to zero.

[ReichhartTom]

I had the same problem today. After a long research I noticed on the import page the dropdown shows Add/Update but the behavior is append. If not ::BEHAVIOR_APPEND is used all affected entries in catalog_category_product are always deleted and then added again with position 0. For whatever reason.

look here: dev/tests/integration/testsuite/Magento/CatalogImportExport/Model/Import/ProductTest.php