Libraries wont show - Display bug?

The libraries that don't show a thumbnail don't have any stock assets in them. If you open these libraries you'll likely see something like 0 items (5 total) when viewed on the Adobe Stock website. You can see all library contents when you view them on https://assets.adobe.com/libraries or from within a Creative Cloud product. On the Stock site you'll only be able to see what Adobe Stock assets are in your libraries.