I have bought assets from the marketplace about a month ago, and they showed up in the library section available for download. In the last week I bought a few more items from the marketplace and they are not showing up in the library to download. I have looked everywhere and can no find anyplace to download them.
Content generally will not show up in the Vault until it is downloaded. You should be able to download it if you click on the content. When you do this, do you see the yellow download button on the right?