RAK3172 ADC not working after deep sleep

I am using the AnalogIn api to measure battery voltage on the rak3172 using the code below.

#include "mbed.h"
AnalogIn voltage(PB_3);

int main()
    while (true) {
        float raw_adc;
        float calc_voltage;
        raw_adc = voltage.read();
        calc_voltage = ((3.3f*raw_adc*(5.0f))/(3.0f))*(1.3f);
        printf("\r\nRaw ADC: %f\r\n", raw_adc);
        printf("\r\n Calc Voltage: %f\r\n", calc_voltage);

When deep sleep is locked, the code works perfectly.

Raw ADC: 0.459096
Calc Voltage: 3.282540

Raw ADC: 0.459341
Calc Voltage: 3.284286

Raw ADC: 0.458852
Calc Voltage: 3.280794

Raw ADC: 0.459341
Calc Voltage: 3.284286

Raw ADC: 0.459585
Calc Voltage: 3.286032

However, when deep sleep is unlocked, the loop only runs once before seeming to crash without any error message. The value printed is also incorrect.

Raw ADC: 0.387790
Calc Voltage: 2.772699

Has anyone else experienced similar problems and/or knows how to fix it?