As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
JUST AFTER TAKEOFF FROM CVG THE FLIGHT CREW REPORTED THAT THE LT FUEL QUANTITY SHOWED ZERO AND RECEIVED A FUEL IMBALANCE MESSAGE. THE FLIGHT RETURNED TO THE FIELD AS A PRECAUTION AND PERFORMED A NORMAL LANDING. MAINTENANCE INSPECTED THE AIRCRAFT AND FOUND IT SAFE TO PLACE THE LT FUEL QUANTITY INDICATION ON MEL. THE MEL WAS CLEARED THE FOLLOWING DAY WHEN MAINTENANCE REMOVED AND REPLACED THE FCU. ALL OPERATIONAL CHECKS WERE SATISFACTORY.