I'm intending to connect VCC/VPA to 3.3V and VDD/VPA to 1.8V. Could you please verify that in that configuration the HDTI and MODE pins are referenced to 1.8V? I.e. If they were pulled up to 1.8V that would be the correct strapping. The diagrams in the datasheet only note a configuration where all power rails are set to 3.3V.
Also, figure 43 of the datasheet recommends a resistor of ~33kohms for R3. Is there a way to derive what this value should be?