Thanks a lot Friend,
From Wednesday, I checked with my couple friends, they did not have same situation as me this week, their details were remain "submitted" all the time. So I guess this would not be a bug to everyone.
Based on the experience from Medical Exam passed Message, If you saw a "updated", it will show "Updated" all the time until you click in to see the application details, after you click View the message, then it will changed to Submitted since you have read it.
I did some search and ask someone else, most of them said this situation would happen when you stuck at certain stage for a very long time, and when "Updated" shown but nothing new came out could mean some officer have started to view your file now. Depending on what stage your application is at, different things can happen.
For me, I have stuck at NA2 for about 2 months, I hope this is would be true and I can have some updates soon.