I don't understand why upsell doesn't show 1 product in the frontend. All upsell products are showing up except for 1. I've reindexed all data, but still no changes. All upsell products are in stock, they all have quantity and they are all enabled, but still 1 product doesn't show up in the frontend. I've tried to check only 1 product, which is the product that is missing but didn't show up, any help, please. Thanks. By the way, it is not modified in the catalog.XML so the product limit is not the issue.