Unconfirmed reports of 485 package refusals

- One highly-skilled professional's package, hand-delivered by employer's attorney to USCIS (NSC) was apparently not accepted
- One would expect that they open the package and send it back with a letter stating a reason for refusal
- What evidence can an applicant present in such a situation that his package was attempted to be delivered? (no fedex tracking number or other such reference).