A product shows zero articles

Read the message on its card — each one means something specific:

• No help URL configured — source is Remote feed and the URL box is empty.
• No local post type configured — source is Local and the post-type box is empty.
• No help provider is configured for this product — source is Read from the plugin directly and nothing answered. Any articles that were cached for that product have just been deleted.
• No message at all, just a dash — source is Remote feed with no URL, so the product is skipped entirely and no status is recorded.