A user is searching for products by way of the Advanced Search dialogue box in PromoMats Vault. Some products are not appearing in the drop-down list even though these products are available filters in the Library. Product Name is a part of the Searchable Object Fields.
This is working as designed.
The Advanced Search only shows products that are referenced in a document. The lookup filter list shows all available products, regardless of whether they are referenced in a document.
Vault Search Documentation: How to Use Advanced Search