The group has to have access to the root folder (Public Folders) in order to see any of the folders inside it. In Folders in the CMC, go to the Manage menu and select Top-Level Security >> All Folders. For the Everyone group, don't assign an access level. Instead, go to the Advanced tab and click on Add\Remove rights. Under General, scroll down and grant "View Objects" then uncheck the right-most check box for that line so that it applies only to the root folder itself. Click on OK twice and then on Close.
This will grant everyone access to the root folder, but not to anything inside it. Since you've already given your new user group access to the new folder, that user should now be able to see the folder in BI Launchpad.
-Dell