ADC channel P02 and P01 always read 0 using external divider

Dear Dialogue support,

So far we are struggling to get ADC on P02/P01 working using external divider - tried both da14585 basic kit and our own board, same behavior.

When we use to external divider, we always get battery reading of 0 while the voltage on the pin is 1.050v - used 2M/1M ohm voltage divider to connect to P02 or P01.
Switching to internal ADC_CHANNEL_VBAT3V reading 100%. With 1.050v applied on P02 and using internal GP_ADC_ATTN3X enabled, always get raw adc (8 bit) about 0x2F.

And have configured the following in user_periph_setup.h:

#define ADC_PORT GPIO_PORT_0
#define ADC_PIN GPIO_PIN_2

and

RESERVE_GPIO( ADCX, ADC_PORT, ADC_PIN, PID_ADC);

in GPIO_reservation function, and

GPIO_ConfigurePin( ADC_PORT, ADC_PIN, INPUT, PID_ADC, false);

in set_pad_function.

Here is the modified adc_get_vbat_sample.

uint32_t adc_get_vbat_sample(bool sample_vbat1v)
{
#define TEST_BATT 1
uint32_t adc_sample, adc_sample2;

#if TEST_BATT
adc_init(GP_ADC_SE, GP_ADC_SIGN, 0);
#else
adc_init(GP_ADC_SE, GP_ADC_SIGN, GP_ADC_ATTN3X);
#endif
adc_usDelay(20);

if (sample_vbat1v)
adc_enable_channel(ADC_CHANNEL_VBAT1V);
else
#if TEST_BATT

#warning "used p02"
adc_enable_channel(ADC_CHANNEL_P02);
#else
adc_enable_channel(ADC_CHANNEL_VBAT3V);
#endif

adc_sample = adc_get_sample();

adc_usDelay(7);

#if TEST_BATT
adc_init(GP_ADC_SE, 0, 0);
#else
adc_init(GP_ADC_SE, 0, GP_ADC_ATTN3X );
#endif

if (sample_vbat1v)
adc_enable_channel(ADC_CHANNEL_VBAT1V);
else
#if TEST_BATT
adc_enable_channel(ADC_CHANNEL_P02);
#else
adc_enable_channel(ADC_CHANNEL_VBAT3V);
#endif
adc_sample2 = adc_get_sample();

//We have to divide the following result by 2 if
//the 10 bit accuracy is enough
adc_sample = (adc_sample2 + adc_sample);
adc_disable();

return adc_sample;
}

Please note we have " #define TEST_BATT 1 " above.

Is there anything else we've missing?

Thanks for your attention,
uta_lc