Answer
Sometimes, a structured product, such as a turbo or warrant, does not have an 'ask' price. In such cases, it's in a so-called 'Bid Only' status. This can occur when the product is sold out or when the maximum leverage allowed by local regulators has been exceeded.
Whenever a product is in this 'Bid Only' status, the issuer or liquidity provider (market maker) can no longer offer to sell (more of) these products to the market. The issuer will therefore not show any 'ask' prices and will only show 'bid' prices at which it offers to buy back any products.
For more information about the status and price information of a particular product, please consult the issuer's or exchange's website.