LTM8047 isolated gate drive power supply

I am using the LTM8047 for a low side isolated gate drive power supply. I am also using it for a high side isolated gate drive power supply.

what is the CMTI rating of this PS?

I am having an issue, as I increase the input line voltage in my inverter application. the output voltage of the low side LTM8047 is decreasing. What could be potential causes? It decreases until the 7V reaches 3V, which is the UVLO cutoff of the isolated gate driver.

I have verified grounding is not an issue, and even tied input and output grounds together to remove this possibility.

I have also verified that the LTM8047 part is not overloaded, as I am drawing 30mA with 230mA max load capability of the device. (15Vin, 7Vout).

Any help or suggestions would be appreciated.