Hello,
in the datasheet of TIDA-01505, it's indicated that the minimimum required start-up current is 103mA. With current of 103mA and Vin_min 50V, we obtain a resistor of 313ohms but in your, you use six resistors of 50ohms, what is the reason if the required resistor is 313ohms? then the maximum start-up current is 3.3mA and not 103mA