Notice Was Returned To USCIS Because The Post Office Could Not Deliver It

Hello,

So this is not DACA related but it is USCIS realted.
I have filed my I 751 ROC on March 11th, on March 22nd I have received a copy of my 18-month extension. The Original was sent to my attorney. My Attorney did not receive the original. I need the original so I can provide a proof of status to my employer. When I check the case status it says

"Notice Was Returned To USCIS Because The Post Office Could Not Deliver It
n March 28, 2019, the Post Office returned a notice we sent you for your Form I-751, Petition to Remove Conditions on Residence, Receipt Number xxxxxxxxxxxxx, because they could not deliver it. This could have a serious effect on your case. Please go to www.uscis.gov/e-request to request a copy of the notice immediately. If you move, go to www.uscis.gov/addresschange to give us your new mailing address."

Please let me know if you have seen this before and if so what did you do?

This happened to me with my current AOS through marriage.

Wife and I submitted I-130 back in October. We were concerned that we didn't receive anything, especially since they cashed the check shortly after we shipped the documents.

We called USCIS and they opened a case. We received a notice a month later with a Case#, which I used to look up through USCIS and the status was the same one you quoted. We requested a copy of the notice following the link www.uscis.gov/e-request. We received a letter late last week letting us know that they received our request to receive a copy of the notice and we will get it within 30 days. Currently waiting for it. If there hasn't been any delay on the back end, the I-130 should be approved within the next two months.

This happens often. The post office failed to deliver an important letter regarding my sister’s case. Set her back a year because she had to do everything over. She is a citizen now