The National Background Investigation Bureau (NBIB) is a government agency within the United States Office of Personnel Management (OPM) and is important for people in the United States undergoing a background check for jobs that require a clearance. NBIB is semi-autonomous and works closely with the DoD, to the point where they are currently being absorbed by the DoD.
The DoD is not affected by the shutdown, but the OPM is partially affected. The NBIB site is silent on the matter and no source I have found confirms or denies the operational status for this specific shutdown.
Are NBIB operations affected by the 2018 - 2019 government shutdown?