Finally, I received a email from architect-submit_US@oracle.com
said they got my assignment and
my assignment has been sent to assessor to grade.
I would suggest anyone who is still waiting for your result and not sure if they got your assignment just sent your assignment again and
use another email account (better use non-commercial account).
In my case, I used Gmail account to send them my assignment on 4/21 and never got any response even I sent a bunch of emails to ask them the status.
So last week I used my another account, which is a school email account to send them my assignment again and today I got a email from them.
I doubt they never received my email sent via Gmail account.
So don't just wait! If you are not sure whether they got your assignment, just try to sent it again via a different email account.
Also make sure you got a reply from them within two weeks after you sent your assignment.