MkrFox1200 sleep rtc problem

Hello

When using the ArduinoLowPower sleep function my device does not get out of sleep mode;

SigFox Simple Weather Station

 This sketch demonstrates the usage of MKRFox1200 as a simple weather station.
 It uses
   the onboard temperature sensor
   HTU21D I2C sensor to get humidity
   Bosch BMP280 to get the barometric pressure
   TSL2561 Light Sensor to get luminosity

 Download the needed libraries from the following links
 http://librarymanager/all#BMP280&Adafruit
 http://librarymanager/all#HTU21D&Adafruit
 http://librarymanager/all#TSL2561&Adafruit
 http://librarymanager/all#adafruit&sensor&abstraction

 Since the Sigfox network can send a maximum of 120 messages per day (depending on your plan)
 we'll optimize the readings and send data in compact binary format

 This example code is in the public domain.
*/


#include <SigFox.h>
#include <ArduinoLowPower.h>
#include "conversions.h"

// Set oneshot to false to trigger continuous mode when you finisched setting up the whole flow
int oneshot = false;


#define STATUS_OK     0
#define STATUS_BMP_KO 1
#define STATUS_HTU_KO 2
#define STATUS_TSL_KO 4

/*
   ATTENTION - the structure we are going to send MUST
   be declared "packed" otherwise we'll get padding mismatch
   on the sent data - see http://www.catb.org/esr/structure-packing/#_structure_alignment_and_padding
   for more details
*/
typedef struct __attribute__ ((packed)) sigfox_message {
 uint8_t status;
 int16_t moduleTemperature;
 uint8_t lastMessageStatus;
} SigfoxMessage;

// stub for message which will be sent
SigfoxMessage msg;
int temperature;
void setup() {

 if (oneshot == true) {
   // Wait for the serial
   Serial.begin(115200);
   while (!Serial) {}
 }

 if (!SigFox.begin()) {
   // Something is really wrong, try rebooting
   // Reboot is useful if we are powering the board using an unreliable power source
   // (eg. solar panels or other energy harvesting methods)
   reboot();
 }

 //Send module to standby until we need to send a message
 SigFox.end();

 if (oneshot == true) {
   // Enable debug prints and LED indication if we are testing
   SigFox.debug();
 }

 

}

void loop() {
 // Every 15 minutes, read all the sensors and send them
 // Let's try to optimize the data format
 // Only use floats as intermediate representaion, don't send them directly

 
 // Start the module
 SigFox.begin();
 // Wait at least 30ms after first configuration (100ms before)
 delay(100);

 // We can only read the module temperature before SigFox.end()
 temperature = SigFox.internalTemperature();
 msg.moduleTemperature = convertoFloatToInt16(temperature, 60, -60);

 if (oneshot == true) {
   
  
   Serial.println("Internal temp: " + String(temperature));
  
 }

 // Clears all pending interrupts
 SigFox.status();
 delay(1);

 SigFox.beginPacket();
 SigFox.write((uint8_t*)&msg, 12);

 msg.lastMessageStatus = SigFox.endPacket();

 if (oneshot == true) {
   Serial.println("Status: " + String(msg.lastMessageStatus));
 }

 SigFox.end();

 if (oneshot == true) {
   // spin forever, so we can test that the backend is behaving correctly
   while (1) {}
 }

 //Sleep for 15 minutes
 LowPower.sleep(1 * 60 * 1000);
}

void reboot() {
 NVIC_SystemReset();
 while (1);
}