I think in your case the product is out of stock due to which its not shown in vendor shop.
Products will be shown only when it fulfills the following conditions:
1.the product should be in stock.
2.the quantity of the product should be greater than zero.
3.Create a subcategory in the default category and assign your product to this category. In this way your product becomes searchable.
4.Also keep the category setting “Is Active” enabled.
5.keep in mind that in case you are creating a configurable, bundle or group product do not forget to assign them their associated products.
