XBee End Device - AD0 Pin State During Sleep

XBee novice here, following through Faludi’s book. Built the simple wireless sensor network with sleep example, and I have a question about the end devices. For this example, the sensor is an LM335 biased at about 1 mA, with the output on a 3:2 voltage divider to provide an output in the range of the XBee analog input (up to 1.2V). When I had theses nodes configured as routers, and I measured the voltage at AD0, I got about 1 V, which is what I expected. However, after converting the nodes to end devices, when sleeping, AD0 seems to be pulled up to Vcc, resulting in a significant current draw, lowering battery life. I tried turning off the pull up resistor setting ATPR with the correct mask, but I still see the pin driven high. Any suggestions or comments? I’m just trying to learn the right techniques to minimize battery draw for remote sleeping sensors.
Thanks in advance.

What happens if you add a Pull down resistor to the line?