Trouble setting timer interrupts

Question

Following my last post a few days ago, I was finally able to communicate with a slave via the TWI interface, thank you very much for your help! This time, I have a problem concerning timer interrupts. Basically, I can't get one : the program seems to never enter the timer_handler. I have followed the same procedure as in the timer example (altough I am using nrfx_timer instead of nrf_drv_timer). The other difference being that my nrfx_config.h file does not call on a sdk_config.h file (I have taken the nrfx_config.h file located in the templates folder for nRF52832). 
 
 So what could it be? I suspect it could be linked to my project not having a sdk_config.h file of sorts but it seemed to be working fine without it when I was testing the TWI communication. I also read somewhere that it was the SoftDevice that was controlling the timers, could that be interfering with my code? 
 
 I have included the TWI section of my code for context in case one interferes with the other but I doubt that it does. 
 #include <stdio.h>
#include "nrf_gpio.h"
#include "nrfx_timer.h"
#include "nrfx_twi.h"

//-----------------------------------------------------------------------// TEMPS
const nrfx_timer_t m_timer = NRFX_TIMER_INSTANCE(0);

void timer_init(void)
{
 const nrfx_timer_config_t timer_config =
 { 
 .frequency = NRF_TIMER_FREQ_1MHz,
 .mode = NRF_TIMER_MODE_TIMER, 
 .bit_width = NRF_TIMER_BIT_WIDTH_32,
 .interrupt_priority = NRFX_TIMER_DEFAULT_CONFIG_IRQ_PRIORITY, 
 .p_context = NULL 
 };

void timer_handler(nrf_timer_event_t event_type,void* p_context)
{
 switch(event_type)
 {
 case NRF_TIMER_EVENT_COMPARE0:
 {
 nrf_gpio_pin_toggle(17);
 break;
 }

 default:
 {
 break;
 }
 }
}

 nrfx_timer_init(&m_timer,&timer_config,timer_handler);
 uint32_t time_ticks = nrfx_timer_ms_to_ticks(&m_timer,500);

 nrfx_timer_extended_compare(&m_timer,NRF_TIMER_CC_CHANNEL0,time_ticks,NRF_TIMER_SHORT_COMPARE0_CLEAR_MASK, true);
 nrfx_timer_enable(&m_timer);
}

//-----------------------------------------------------------------------// ADDRESSAGE
#define ADDR 0x20 // 0x20 &#224; 0x27

const nrfx_twi_t m_twi = NRFX_TWI_INSTANCE(0);
uint8_t dirA[2] = {0x00,0x00};
uint8_t ioA[2] = {0x0A,0x00};

uint8_t conf[2] = {0x05,0xA0};

void twi_init(void)
{
 const nrfx_twi_config_t twi_config =
 {
 .scl = 27,
 .sda = 26,
 .frequency = NRF_TWI_FREQ_100K,
 .interrupt_priority = NRFX_TWI_DEFAULT_CONFIG_IRQ_PRIORITY,
 .hold_bus_uninit = false,
 };

 nrfx_twi_init(&m_twi,&twi_config,NULL,NULL);
 nrfx_twi_enable(&m_twi);
}

//-----------------------------------------------------------------------// MAIN
void main(void)
{
 timer_init();

 nrf_gpio_pin_dir_set(17, NRF_GPIO_PIN_DIR_OUTPUT);

 nrf_gpio_pin_dir_set(18, NRF_GPIO_PIN_DIR_OUTPUT);
 if(nrfx_timer_is_enabled(&m_timer) == 1) nrf_gpio_pin_clear(18);

 while(1)
 {
 
 }
}