just check the status online of USciS using your track number. if it says your notice has been mailed, that that means they really already have done. if you still did not receive it, that means it lost.
l*z
8 楼
Thanks! it says they mailed the notice a month ago, so very likely lost. I did the service request with the uscis representative. He told me I will be contacted in 15 days. Any idea what's next for this kind of case?