Staging configuration is always stored in the type settings of the parent live group. That is the group associated to the site in live.
But the methods isStaged(), isStagedPortlet(portletId) and isStagedRemotely() are reading the typeSettings from the current group instance. So if this methods are invoked for a group instance that represents staging or a layout scope the settings are not found. Those methods should make sure that they always check the type settings of the live parent.