MP 2659 3 cell configuration not able to load beyond 30mA

In one of my applications, I amusing MP2659 as the battery charger with the below configuration,
Vin= 19-22V ; VBATT_REG=> VB set to 4.2V, CELL set to 3 => 12.6V(Typ) and ICC = 1A. But during testing its is found that the charger is tripping beyond 30mA load.
Where as the same PCBA is configured for 4 cell and 5Cell, It was working fine and able to load the set Icc of 1A.
What could be the reason for this issue? Pls check and reply