This feature is available in all editions.
Some users can't see backlog items in a child project when they have a parent project selected. We have the same permissions and I can see both parent and child stories. What can cause this?
This is probably due to the user's project selection in the Project Tree.
It sounds like the Single Level Project View option is selected. This option only displays items from the selected project and excludes items that belong to child projects below. The highlighted projects under My Projects shows the currently selected project (the default is for this setting to be off).
To fix this:
Click on the Project Navigator, and then click on the Project Tree tab.
Select a project, and then deselect Single-level Project View check box.