As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
MISC/DE ON APPROACH IN ATL WHEN FLAP HANDLE WAS MOVED TO 20, "LE SLAT ASYMMETRY" MESSAGE DISPLAYED, FLAP INDICATOR INDICATED 20. CREW DISCONTINUED APPROACH AND EXECUTED MISSED APPROACH PROCEDURE, CONSULTED QRH FOR LEADING EDGE SLAT ASYMMETRY AND DECLARED EMERGENCY WITH ATC. CORRECTIVE ACTION: REPLACED PSEU ON LP 1653488. SYSTEM OPERATION IS NORMAL.