External Attenuator Configuration Issues

I am using the No-OS API to configure my AD9371 and now I want to control an external attenuator.  My problem is that I am monitoring the 3.3V GPIOs and I do not see the proper voltages on the GPIO lines. Instead of seeing 3.3V for all the pins, I see some strange voltage from 0.3V to 2.5V. Note that I am using a custom board where the GPIO lines are just fed out to a header.

Here is what I am doing to set up the device:

1. I edited the gain table such that the external attenuation field is 15 for index 255. As a result, I expect to see 3.3V on all GPIO lines.

2. I set up manual gain mode on both RX1 and RX2 to use index 255.

3. I set up my 3.3V GPIO structure as shown:

static mykonosGpio3v3_t gpio3v3 = {
  0x00FF,
  GPIO3V3_EXTATTEN_LUT_MODE,
  GPIO3V3_EXTATTEN_LUT_MODE,
  GPIO3V3_BITBANG_MODE
};

4. I follow the steps from headless.c and simply call MYKONOS_setupGpio3v3() after MYKONOS_setupGpio()

Is there anything wrong with my configuration? Why am I not seeing the proper GPIO values?