Just found this on ilw....
For the full USCIS memo, see here
USCIS Revises Name Check Policy
USCIS previously required that the FBI name check clearance be obtained before any immigration benefits applications were approved, regardless of the length of time required for the FBI name check approval. USCIS issued a revised FBI name check policy,
"Where the application is otherwise approvablc and the FBI name check request has been pending for more than 180 days, the adjudicator shall approve the 1-485,1-601,1-687, or 1-698 and proceed with card issuance. The FBI has committed to providing FBI name check results within this timeframe."
For the full USCIS memo, see here