Four common reasons for an ASIN being unsearchable are:
To enable Variation Elimination to work, parent ASINs are not searchable or buyable. A parent ASIN forces customers to select a color or/and size:
In order to be searchable, ASINs need to be assigned to a browse node. A browse node is like a shelf in a supermarket. Your product needs to be on a “shelf” in order to be found.
Unassigned ASINs are not indexed by Amazon Search.
You can use the Product Classifier or a Browse Tree Guide (BTG) to help you identify the correct categories for your products.
Example
This ASIN is nicely-assigned to the specific browse node called “Bubble Bath”:
ASIN browse assignments “roll up”. In this example, the ASIN will appear in Bubble Bath and in Bath and in Bath & Shower Accessories and in the overall Beauty category on Amazon.
Tip: Some ASINs are searchable in All Product Search (APS), but not within Departments on Amazon. This is because they were not assigned to a browse node, so were automatically assigned to a category called Everything Else. Assigning your ASIN to a specific, relevant browse node will ensure that your product doesn't end up in Everything Else.
In order to be searchable, an ASIN needs an offer. If an ASIN's offer expires, this would cause it to become unsearchable.
To add an offer to a product, you need to supply data such as Item Price, Quantity, and Launch Date.
You can add offers one at a time via Add a Product or in bulk via inventory templates.
A common reason for an ASIN being unsearchable is because it has a future launch date. In other words, it is not yet possible to buy the product.
To be searchable, an ASIN's launch date must be in the past.
In templates: launch-date
In feeds(Product.xsd): LaunchDate