The code below holds the publishingStorage created at the time the monitor is created. So it's completely different object after the publishing module restart resulting in an empty activation monitor report.

    @Inject
    public PublishingMonitor(Provider<PublishingCoreModule> publishingCoreModuleProvider) {
        MBeanUtil.registerMBean("PublishingMonitor", this);
        this.publishingStorage = publishingCoreModuleProvider.get().getPublishingLogStorage();
    }

This used to be an issue in the old activation as well, see info.magnolia.module.activation.monitor.ActivationMonitor#ActivationMonitor. But now there is high change to hit the issue, since we moved all the config under the module (it used to be only config for the activation storage itself).