Here's what I found but does not say anyting about 485 denial because of USCIS error.
Deferred Inspection
Deferred inspection means that the person does not meet the legal requirements for admission, but the INS Inspector has reason to believe that the applicant will be able to correct the problem and provide the necessary information after entering the U.S. Therefore, the applicant is admitted on a provisional basis, with instructions to return to the Port of Entry at a later date. The Applicant must have made good faith efforts to comply with the requirements of advance parole prior to departure.
Circumstances in which deferred inspection is appropriate :
(a) The Officer was satisfied that the applicant left the U.S. with a valid Form I-512 and was unable to return before it expired due to unforeseen, uncontrollable, and compelling circumstances beyond her/his control.
(b) The Officer was satisfied that the applicant applied for advance parole in a timely and proper manner before leaving the U.S. and that departure prior to INS response was due to compelling and uncontrollable circumstances.
Officers can accept an INS receipt or canceled check endorsed by INS or other appropriate evidence, as verification that Form I-131 was properly filed in the above circumstances. Alternatively, the inspector can check the location of the adjustment of status application to confirm if Form I-131 was filed.
(c) The Officer is satisfied that the applicant was notified of the approval of the adjustment of status application prior to the date of departure from the U.S. However, that the applicant had to depart so urgently that he/she was unable to report to the INS office to complete final stages of the adjudication process.
Officers may accept evidence such as a Notice of Action (Form I-797), INS district approval notice or status check in the INS "CLAIMS" database, if available, in order to establish adjustment of status was granted in the above circumstance.
Another common situation, not specifically mentioned in the INS memo but previously authorized in INS instructions, is if the I-485 application is approved after the applicant's departure from the U.S. In that circumstance, it is typical to grant deferred inspection, so that the person can go to the local INS office and obtain the permanent residency stamp in the passport.
Deferred Inspection at Port of Entry
When deferred inspection is deemed appropriate, the applicant should be deferred to the INS office with jurisdiction over her/his current place of residence in the U.S. Deferment will provide the officer with an opportunity to obtain additional information necessary to make an accurate decision on the status of the pending I-485 application. The I-94 card will be endorsed with the parole stamp and with “DE, Deferred Inspection.” The applicant will be paroled for a reasonable period, to allow for paperwork to arrive at the appropriate office and for the applicant to obtain any necessary evidence. The applicant then needs to return to the Port of Entry at a designated time.
Deferred Inspection at INS Office
If the local INS office confirms that the I-485 was approved, parole should be terminated and the applicant admitted for permanent residence. If an approved / pending application is not located at the particular INS office conducting deferred inspection, the particular INS District office or Service Center which has the application should be contacted before a final determination is made.
If the inspection is deferred due to a pending I-131 or expired I-512, the immigration office conducting the deferred inspection should review the status of the application and then decide whether to continue or terminate the pending I-485; to request the applicant to re-file or, when appropriate, to place the applicant in removal proceedings.
