Depending on whether auto-approval for user-submitted resources on a Hub is turned On/Off, which can be done in each component's settings (Options), you may need to watch for newly submitted content awaiting for administrator approval to be published on the Hub. The administrative dashboard shows whether content is pending approval by component.

You can publish a pending piece of content just by clicking on the title and select appropriate status from the detailed page, as shown below.

As soon as new content is published, it will be available for Hub users to access and search the item, depending on access restrictions.