so I just got off the phone with IRCC call center. The agent I spoke with was very helpful. She tried to track down my application using several different methods, including payment receipt, UCI, and at the end just my name. She assured me that my application is not returned since for any returned application, there would be a note on the file. She also said that my payment has not been cashed out. after failing to track down the app, she told me that I either have to wait a bit more or resend the application again. she also suggested me to put a copy of 'certificate of delivery' on my new application and explain why I am sending a second application [in case the first one shows up].
at the end of my phone call I asked her if she would be able to let someone at Sydney know that there are number of missing applications from Oct 13th. She was very surprised and told me it's the first time someone from Oct 13th asking her about a missing application. I know they have many agents and it's matter of chance who pick up the phone but it's interesting that not many of us from Oct 13th seem to have this problem.
anyway, thought to share this with you guys. it may help you to decide to reapply or wait.