ADP1074 Oscillation at Low Output Voltages

I am trying to simulate a forward converter using the ADP1074 with the following specifications:

15V input

1.5V, 1A output

Fsw = 500 kHz

Auxiliary secondary winding to generate 6V for VDD2

I have been able to successfully generate outputs up to 30V, but anything below 5V output and I run into oscillation/stability problems.

I have tried modifying values in the compensation network, but it doesn't seem to have an effect

I have attached my ltspice circuit.