Sometimes the tools being used to access the Career Portal feed and post jobs on Facebook or Twitter do not update in a timely manner. This may leave jobs on your social media sites that are linked to posts that have been removed from the Career Portal (so they look blank.) This is not a problem with the Career Portal. The feed from the Career Portal is dynamically created and is always current.
The problem will resolve itself when the tool you are using updates the posts from the feed. In some cases, depending on the tool, you can manually force this update. Please check the documentation for the feed tool you are using for more information.