LM5117 design from WebBench does not work as expected. Any suggestions?

We have implemented a test circuit with the LM5117 for the following Design Inputs:
#    Name       Value            Description
1.    Iout           3.0 A             Maximum Output Current
2.    Iout1         3.0 Amps    Output Current #1
3.    VinMax      55.4 V          Maximum input voltage
4.    VinMin      18.0 V          Minimum input voltage
5.    Vout           12.0 V         Output Voltage
6.    Vout1         12.0 Volt     Output Voltage #1
7.    base_pn   LM5117      National Based Product Number
8.    source      DC               Input Source Type
9.    Ta             30.0 degC   Ambient temperature

 We modified the WebBench circuit to add a Low Pass filter to the LM5117 Vin pin (consisting of a 4.99 Ohm series and a 1uF Ceramic to ground)and an additional power input bulk Capacitor (68uF 100V).

We started testing the circuit and the regulation looked good at lower Vin (<26V), but as we increased the Voltage Input, the circuit fails.  The high side MOSFET, LM5117, and Cout has failed on several boards (or some combination of the three parts).

We did add (5 Ohm) series resistors to the gate drives HO and LO and it seems slightly better, but still fails.

Any help or suggestions?

Thanks,