AFE4900EVM: LED1 data output showing constant value instead of meaningful data

When collecting PPG data using the board and PPG sensor, the LED2 and LED3 outputs show meaningful data, but the LED1 output shows only a constant 1.2V, as seen below in the screenshot of the software.  According to the manual LED1 should correspond to the green LEDs, LED2 to the red LED, and LED3 to the infrared LED.  The green LEDs appear visually to be working on the sensor.