What is output load impedance and voltage at time of input short to ground.
edit...
Show block diagram of two input series supplies , your design , load capacitance , current and voltage and where is 30V SMPS?
Is there large series input inductance (uH) between source and where short to ground was applied?
If so, then inductive kickback (+) V=L*di/dt when short is removed and if pot is set to 0,
Absolute MAX input output differential is 37Vmax.
Otherwise consider increasing both Pot and Fixed R 240 values so you never exceed power dissipation with >>> 1.25V across resistor from a shorted input.
Just guessing since you did not provide details on design.[