> ## Documentation Index > Fetch the complete documentation index at: https://help.maestra.io/llms.txt > Use this file to discover all available pages before exploring further. # Why Recommendations Aren't Showing or Are Wrong When a recommendation block comes back empty — or shows products that don't make sense — the cause is almost always one of a small set of things: a product is out of stock, the customer's zone is missing items, a segment is empty, or the customer doesn't have the behavior the algorithm needs. This page walks through each algorithm and lists every reason it might return no products, plus what to check. ## How to read this page Algorithms fall into two groups: * **Event-based algorithms** depend on something the customer did — a view, a session, an order. If the customer has no relevant events, the algorithm has nothing to work with. * **Non-event algorithms** rank products against the whole catalog (or a category). They don't need customer behavior, so the troubleshooting usually points at the product feed or a segment. For every algorithm below, work through the listed reasons in order. The first three — out of stock, zone mismatch, empty segment — cover most cases. ## Event-based algorithms ### Event-based personal recommendations **Why no products appear** * No products in stock anywhere in the project. * No products available in the customer's zone. * The source segment is empty. * Products exist in the segment, but none are available in the customer's zone. **What to check** * Whether the chosen segment actually contains products. * The YML feed for stock status. * Regional availability settings. ### Popular products in viewed categories (last session) **Why no products appear** * No products in stock in the project. * No products available in the customer's zone. * The source segment is empty. * Products are in the segment but not available in the customer's zone. * Products exist in the viewed categories but not in the customer's zone. * The customer didn't view any categories. **What to check** * Whether the customer has category-view events. * Whether those views happened inside the session window (a session is 2 hours). ### Recently viewed products **Why no products appear** * Products are out of stock. * Products aren't available in the customer's zone. * The source segment is empty. * Products are in the segment but not in the customer's zone. * The customer has no view history. * All views are older than 14 days. **What to check** * Whether view actions exist for the customer. * Whether the views fall within the 14-day window. ### Related products to the last order **Why no products appear** * Products are out of stock. * Products aren't available in the customer's zone. * The target segment is empty. * The target segment has products, but none are available in the customer's zone. * The customer has no order history. * None of the customer's ordered products belong to the target segment. * No orders fall inside the configured time window. **What to check** * The customer's order history. * Whether ordered products belong to the target segment. ### Manual category mapping to the last order **Why no products appear** * Products are out of stock. * Products aren't available in the customer's zone. * The target segment is empty. * The target segment has products, but none are available in the customer's zone. * The customer has no order history. * None of the customer's ordered products belong to the target segment. * The recommended category is empty in the customer's zone. * No exact field match exists between source and target products. **What to check** * The customer's order history. * Product availability in the recommended category. * Whether the similarity fields match exactly. ### Similar products to those viewed in the last session **Why no products appear** * Products are out of stock. * Products aren't available in the customer's zone. * The source segment is empty. * Products are in the segment but not in the customer's zone. * No exact field match between viewed and candidate products. * The customer has no view history. * The viewed products aren't part of the target segment. **What to check** * Views during the customer's session. * Whether the similarity fields match across the two segments. ### Related products to a product list **Why no products appear** * Products are out of stock. * Products aren't available in the customer's zone. * The source segment is empty. * The source segment has products, but none are available in the customer's zone. * The customer's product list is empty. * No orders fall within the configured time window. * Products in the list don't belong to the target segment. **What to check** * The products in the customer's list. * Their availability in the customer's zone. * Order statistics across the period. ### Similar products to a product list **Why no products appear** * Products are out of stock. * Products aren't available in the customer's zone. * The target segment is empty. * The target segment has products, but none are available in the customer's zone. * No exact field match between list products and candidates. * The customer's product list is empty. * The list's products aren't available in the customer's zone. **What to check** * That the customer's product list isn't empty. * That similarity fields match. * Availability in the customer's zone. ## Non-event algorithms ### Personal recommendations **Why no products appear** * No products in stock anywhere in the project. * No products available in the customer's zone. * The source segment is empty. * Products are in the segment but not in the customer's zone. **What to check** * The segment for product availability. * YML feeds. * Regional availability. ### Manual category mapping **Why no products appear** * Products are out of stock. * Products aren't available in the customer's zone. * The target segment is empty. * The target segment has products, but none are available in the customer's zone. * The customer has no order history. * The target segment is empty for this customer. * The recommended category is empty in the customer's zone. * No exact field match exists. **What to check** * Availability in the target segment. * Whether the recommended category has products in the zone. * That similarity fields match. ### Related products **Why no products appear** * Products are out of stock. * Products aren't available in the customer's zone. * The source segment is empty in the customer's zone. * The target segment is empty in the customer's zone. * No orders fall within the configured time window. **What to check** * Availability in both segments inside the customer's zone. * Order statistics for the period. ### Similar products **Why no products appear** * Products are out of stock. * Products aren't available in the customer's zone. * The target segment is empty in the customer's zone. * No exact field match between source and target products. **What to check** * Whether similarity fields match across both segments. * Availability in the customer's zone. ### Popular products by category **Why no products appear** * Products are out of stock. * Products aren't available in the customer's zone. * The source segment is empty. * Products exist in the segment but not in the customer's zone. * The category is empty in the customer's zone. **What to check** * The source segment. * Category-level availability in the customer's zone. ### Popular products **Why no products appear** * Products are out of stock. * Products aren't available in the customer's zone. * The source segment is empty. * Products exist in the segment but not in the customer's zone. **What to check** * The segment. * YML feeds. * The popularity window (30 days by default). If an algorithm returns nothing across the whole project — not just for one customer — start with the YML feed and the segment definition. Those two settings explain almost every project-wide empty result.