@Reference service always null in BundleListener class

I am having issues trying to access a service of mine in a BundleListener. The service (LanguageService) works in different parts of my code outside of the BundleListener (for example my rest endpoints).

Activator:

public class Activator implements BundleActivator {
    @Override
    public void start(BundleContext bundleContext) throws Exception {
        bundleContext.addBundleListener(new PlatformCoreBundleListener());
    }
    ...
}

BundleListener:

@Component(immediate = true)
public class PlatformCoreBundleListener implements BundleListener {
    private static final Logger LOG = LoggerFactory.getLogger("AsAdventure");
    @Reference
    private LanguageService languageService;
    @Override
    public void bundleChanged(BundleEvent bundleEvent) {
        String symbolicName = bundleEvent.getBundle().getSymbolicName();
        if (symbolicName.equalsIgnoreCase(BundleConstants.SYMBOLIC_AEM_PLATFORM_CORE_BUNDLE)) {
            if (bundleEvent.getType() == BundleEvent.STARTED) {
                LOG.info("[PlatformCoreBundleListener]: " + BundleConstants.SYMBOLIC_AEM_PLATFORM_CORE_BUNDLE + " has started.");
            }
        }
    }
}

The languageService is always null even when I take a look at it in debug mode while the bundleEvent has a type of 'STARTED'.

What am I doing wrong? Thanks in advance!