LT3796 as capacitor charger

I'm trying to use the LT3796 as a boost regulator (12-30 in, 45V out) to charge a capacitor bank, but my LTSpice simulation shows the device is in a fault condition and it never toggles the Gate output.

As a sanity check I modified the example simulation, LT3796_TA01A.asc and isolated the problem. As soon as I remove the LED from the circuit and connect straight to GND, the fault appears. I guess this makes sense, as the inrush of Vin (through the inductor and the Schottky diode) is racing through to ground and creating what looks like a short circuit regardless of the state of the rest of the chip.

So, I'm guessing this is more of a topology problem. Is there a way to do what I want, to use the LT3796 to charge caps from 0V up to the CV limit at constant current? SEPIC?

Thank you,

Brian

LT3796_TA01A_modified.asc