As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT RETURNED TO MSP DUE TO LOSS OF LEFT HYDRAULIC SYSTEM QUANTITY AND PRESSURE. AIRCRAFT LANDED WITHOUT INCIDENT AND WAS TOWED TO THE GATE. MAINTENANCE FOUND A DISCONNECTED SUPPLY LINE ON THE ENGINE DRIVEN HYDRAULIC PUMP. REMOVED AND REPLACED THE ENGINE DRIVE PUMP, BRAKE QUICK DISCONNECT AND FILTERS. RECONNECTED THE SUPPLY LINE, TESTED THE SYSTEM AND RETURNED TO SERVICE.