https://github.com/opencart/opencart/pull/13869

upload/catalog/controller/product/compare.php

@@ -99,17 +99,19 @@ public function index(): void {
 				}
 
 				if ($product_info['quantity'] <= 0) {
-					$stock_status_info = $this->model_localisation_stock_status->getStockStatus($product_info['stock_status_id']);
-
-					if ($stock_status_info) {
-						$availability = $stock_status_info['name'];
-					} else {
-						$availability = '';
-					}
+					$stock_status_id = $product_info['stock_status_id'];
 				} elseif ($this->config->get('config_stock_display')) {
-					$availability = $product_info['quantity'];
+					$stock_status_id = 0;
+				} else {
+					$stock_status_id = $this->config->get('stock_status_id');
+				}
+
+				$stock_status_info = $this->model_localisation_stock_status->getStockStatus($stock_status_id);
+
+				if ($stock_status_info) {
+					$availability = $stock_status_info['name'];
 				} else {
-					$availability = $this->language->get('text_instock');
+					$availability = $product_info['quantity'];
 				}
 
 				$attribute_data = [];