Hi @chun!
In general, data in the Analytics module is not real-time. It takes around 30 minutes for it to be processed after being tracked, so it’s possible that there was some not yet processed events waiting in the pipeline.
Not sure if this is your case but it’s still worth mentioning - events tracked via the mobile SDKs (Android, iOS) can be a little bit late. This is because mobile devices (can) lose internet connection pretty often and in this case our SDKs store the tracking requests in local storage until connection is reestablished.