Omission of significant medical records can justify remand to the agency for insufficient development of the factual record where the petitioner suffers from cognitive impairment; the claimant does not have to make a showing of discriminatory effect of the omission.
http://media.ca1.uscourts.gov/pdf.opinions/17-2146P-01A.pdf
Since 2011. An occasional commonplacing of the U.S. Circuit Courts of Appeal.
Neither an authoritative statement of the law nor legal advice. Quick work.