LT8302 switching mode changes to high loss ringing

My LT8302 circuit is stable at power up (Top pic). But if one touched the circuit pin5&6, the IC went into odd oscillation with very high power consumption (Bottom pic) that did not recover when untouched. This happened regardless of the snub component values (with Csnub in the range of 100pF to 470pF, Rsnub in the range of 0ohm to 100ohm)