Box2d Lighting different behavior with different screen size

Question

I tried to play a little with lighting, but very quickly I came upon weird behavior that I dont understand. Could anybody explain to me, why this happens, if it is on purpose, or I do something wrong.

On the first image, light goes little trough obstacle (which is also weird).

When the screen size is changed to lower width, the light goes even more through obstacle.

The red background is "black bar", since I use FitViewport. The "real" world has badlogic.jpg all over it.

On the next pictures you can see, how it works without light rendering - the screen renders the same world regardless of screen size (only scaled). Thats how I would expect it to work even with lighting.

The project is standard, generated by libgdx project generator. All my code is just one class, so I can upload it here:

package com.gobanit.sandbox.main;

import com.badlogic.ashley.core.Engine;
import com.badlogic.gdx.ApplicationAdapter;
import com.badlogic.gdx.Gdx;
import com.badlogic.gdx.Input.Keys;
import com.badlogic.gdx.graphics.GL20;
import com.badlogic.gdx.graphics.OrthographicCamera;
import com.badlogic.gdx.graphics.Texture;
import com.badlogic.gdx.graphics.g2d.SpriteBatch;
import com.badlogic.gdx.math.Vector2;
import com.badlogic.gdx.math.Vector3;
import com.badlogic.gdx.physics.box2d.Body;
import com.badlogic.gdx.physics.box2d.BodyDef;
import com.badlogic.gdx.physics.box2d.BodyDef.BodyType;
import com.badlogic.gdx.physics.box2d.Box2DDebugRenderer;
import com.badlogic.gdx.physics.box2d.CircleShape;
import com.badlogic.gdx.physics.box2d.FixtureDef;
import com.badlogic.gdx.physics.box2d.PolygonShape;
import com.badlogic.gdx.physics.box2d.World;
import com.badlogic.gdx.utils.viewport.FitViewport;
import com.badlogic.gdx.utils.viewport.Viewport;

import box2dLight.PointLight;
import box2dLight.RayHandler;

public class SandboxTestGame extends ApplicationAdapter {
    SpriteBatch batch;
    World world;
    Engine engine;
    Viewport viewport;
    Box2DDebugRenderer debugRenderer;
    Texture texture;
    RayHandler rayHandler;

    Body playerBody;

    @Override
    public void create () {
        batch = new SpriteBatch();
        texture = new Texture(Gdx.files.internal("badlogic.jpg"));
        engine = new Engine();
        world = new World(new Vector2(0, 0), true);
        viewport = new FitViewport(1000, 500);
        viewport.getCamera().position.set(new Vector3(0, 0, 0));
        debugRenderer = new Box2DDebugRenderer();   
        rayHandler = new RayHandler(world);
        rayHandler.setShadows(true);

        createPlayerBody();
        createObstacleBody();       

        PointLight l1 = new PointLight(rayHandler, 100, null, 500, 0, 0);
        l1.attachToBody(playerBody);
        //l1.setSoft(true);

        //new PointLight(rayHandler, 100, null, 500, 0, 200);

    }

    private void createObstacleBody() {
        BodyDef bodyDef = new BodyDef();
        bodyDef.position.add(new Vector2(-10000, 100));
        bodyDef.type = BodyType.StaticBody;

        Body body = world.createBody(bodyDef);

        FixtureDef fixDef = new FixtureDef();
        PolygonShape shape = new PolygonShape();
        shape.set(new float[] {0f,0f,0f,40f,20000f,40f,20000f,0f});
        fixDef.shape = shape;

        body.createFixture(fixDef);

        body.setActive(true);       
    }

    private void createPlayerBody() {
        BodyDef bodyDef = new BodyDef();
        bodyDef.position.add(new Vector2(100, 50));
        bodyDef.type = BodyType.DynamicBody;

        Body body = world.createBody(bodyDef);

        FixtureDef fixDef = new FixtureDef();
        CircleShape circle = new CircleShape();
        circle.setRadius(20);
        fixDef.shape = circle;

        body.createFixture(fixDef);

        body.setActive(true);

        playerBody = body;      
    }



    @Override
    public void render () {
        update();
        draw();
    }

    private void draw() {
        Gdx.gl.glClearColor(100, 0, 0, 1);
        Gdx.gl.glClear(GL20.GL_COLOR_BUFFER_BIT);

        viewport.update(Gdx.graphics.getWidth(), Gdx.graphics.getHeight());

        batch.setProjectionMatrix(viewport.getCamera().combined);
        batch.begin();
        batch.draw(texture, -1000, -1000, 2000, 2000);
        batch.end();

        debugRenderer.render(world, viewport.getCamera().combined);

        rayHandler.setCombinedMatrix((OrthographicCamera) viewport.getCamera());
        rayHandler.render();    
    }

    private void update() {
        world.step(1f/60f, 8, 3);
        rayHandler.update();

        if(Gdx.input.isKeyPressed(Keys.D)) {
            //viewport.getCamera().position.add(new Vector3(1,0,0));
            playerBody.applyForceToCenter(100, 0, true);
        }
        if(Gdx.input.isKeyPressed(Keys.A)) {
            //viewport.getCamera().position.add(new Vector3(-1,0,0));
            playerBody.applyForceToCenter(-100, 0, true);
        }
        if(Gdx.input.isKeyPressed(Keys.W)) {
            //viewport.getCamera().position.add(new Vector3(0,1,0));
            playerBody.applyForceToCenter(0, 100, true);
        }
        if(Gdx.input.isKeyPressed(Keys.S)) {
            //viewport.getCamera().position.add(new Vector3(0,-1,0));
            playerBody.applyForceToCenter(0, -100, true);
        }   

        viewport.getCamera().position.set(new Vector3(playerBody.getPosition().x, playerBody.getPosition().y, 0));
    }

    @Override
    public void dispose () {
        batch.dispose();
        texture.dispose();
        world.dispose();
        debugRenderer.dispose();
        rayHandler.dispose();
    }
}

Thanks a lot. If more information is needed, tell me and I will edit the question.