One reason one of your users might not be able to see any jobs would be if they are set as a sourcer. You can change them back to a normal user by following these instructions:

1.) Click on the Settings tab.
2.) Click on the User Management link in the top blue bar.
3.) Click on the user's name to get into their profile.
4.) Click on the edit button.
5.) Uncheck the checkbox next to Sourcer in the "Categories" section.
6.) Click on the save button.

The official definition of the sourcer is:
Sourcer: No access to companies/contacts. Limited to viewing only job orders to which they've been assigned. Unlimited visibility into the candidates tab.