Debugger not working with Arduino UNO

Hello,
I have arduino uno board with attached funshield and I would like to use the avr-debugger with it. Unfortunately, it does not seem to work.
When I hit debug, the debugger starts loading but then ends and nothing happens. I dont see my variables, nothing. Just a blank screen here:

I have tried both calling breakpoint(); manually and using the red dot. Nothing worked.
For reference, I am adding my source code file and my platformio.ini file.
Any help would be appreciated.

Souce Code:

#include <Arduino.h>
#include <funshield.h>
#include "avr8-stub.h"

constexpr int LEDs[] = {led4_pin, led3_pin, led2_pin, led1_pin};
constexpr int LEDsCount = sizeof(LEDs) / sizeof(LEDs[1]);
constexpr int moduloVal = 16;

int value = 0;

class Button {
  private: 
    enum class State {
      RELEASED,
      PRESSED 
    };
    int pin;
    State currentState;
    State formerState;
    unsigned long lastTimePressed;  // last time the button was physically pressed
    unsigned long nextRepeatTime;
    static constexpr int holdingDetectDelay = 1000;
    static constexpr int holdingDelay = 300;

  public:
    Button(int pin) {
      this->pin = pin;
    }

    void initialize() {
      pinMode(pin, INPUT);
    }

    void updateStatus() {
      unsigned long currentTime = millis();
      bool state = !digitalRead(pin);
      formerState = currentState;
      currentState = state ? State::PRESSED : State::RELEASED;

      if (currentState == State::PRESSED && formerState == State::RELEASED) {
        lastTimePressed = currentTime;
        nextRepeatTime = lastTimePressed + holdingDetectDelay;
      }
    }

    bool wasPressed() {
      return (currentState == State::PRESSED) && (formerState == State::RELEASED);
    }

    bool wasLongPressed() {
      unsigned long currentTime = millis();

      if (currentState == State::RELEASED) {
        return false;
      }

      if (currentTime >= nextRepeatTime) {
        nextRepeatTime += holdingDelay;
        return true;
      }

      return false;
    }

    bool wasLongerPressed() {
      unsigned long currentTime = millis();
      return wasLongPressed() && currentTime - lastTimePressed > 4000;
    }

    bool isHeld(unsigned long currentTime) {
      return (currentState == State::PRESSED) && (currentTime - lastTimePressed > holdingDetectDelay);
    }
};

Button increaseButton(button1_pin);
Button decreaseButton(button2_pin);

void binaryLight (int input) {
  for (int i = 0; i < LEDsCount; i++) {
    auto isEven = input % 2 == 1;
    digitalWrite(LEDs[i], isEven ? ON : OFF);
    input = input / 2;
  }
}

void changeValue(int valueToAdd) {
  value += valueToAdd;
  binaryLight(value % moduloVal);
}

void setup() {
  for (int i = 0; i < LEDsCount; i++) {
    pinMode(LEDs[i], OUTPUT);
  }
  debug_init();

  increaseButton.initialize();
  decreaseButton.initialize();
}

void loop() {
  breakpoint();
  increaseButton.updateStatus();
  decreaseButton.updateStatus();

  if (increaseButton.wasPressed() || increaseButton.wasLongPressed()) {
    changeValue(1);
  }

  if (decreaseButton.wasPressed() || decreaseButton.wasLongPressed()) {
    changeValue(15);
  }
}

and ini file:

; PlatformIO Project Configuration File
;
;   Build options: build flags, source filter
;   Upload options: custom upload port, speed and extra flags
;   Library options: dependencies, extra library storages
;   Advanced options: extra scripting
;
; Please visit documentation for the other options and examples
; https://docs.platformio.org/page/projectconf.html

[env:uno]
platform = atmelavr
board = uno
framework = arduino
lib_deps = jdolinay/avr-debugger@^1.5
debug_tool = avr-stub
debug_port = ttyACM0

Open a PlatformIO CLI and execute

pio debug --interface=gdb -- -x .pioinit

(docs).

What is the output?

Hello,
thank you for help. I managed to find out that I had a missing libcurses 5 library. Although it was not showing at the debugger directly.