Recalculate normals after transformation

Hello, I'm applying 2 transformation on a ofCylinderPrimitive, getting its vertices and adding them into a mesh. I've some trouble recalculating the normals (i need them later in the shaders because i want to calculate the light that the material should reflects).
This is my actual code:

// .h file
    ofCylinderPrimitive root;
    ofLight light;
    ofVboMesh finalMesh;
    ofShader  shader;

// .cpp
void ofApp::setup(){
    ofSetVerticalSync(true);
    ofEnableDepthTest();
    //light
    light.setPosition(500, 500, 500);
    light.enable();
    
    //mesh
    finalMesh.setMode(OF_PRIMITIVE_TRIANGLES);
    finalMesh.enableColors();
    
    //shader, not used at the moment
    //shader.load("shaders_gl3/render.vert", "shaders_gl3/render.frag");
    
    // root
    root.set(branchDimension, branchLenght, radiusSegments, heightSegments, capSegments, false, OF_PRIMITIVE_TRIANGLES);
    root.setPosition(0, 0, 0);
    root.dolly(branchLenght/2);
    root.tilt(90);
    ofMatrix4x4 normalMatrix = root.getGlobalTransformMatrix().getInverse();
    for(auto v: root.getMesh().getVertices()){
        finalMesh.addVertex(v * root.getGlobalTransformMatrix());
    }
    for(auto i: root.getMesh().getIndices()){
        finalMesh.addIndex(i);
    }
    for(auto i: root.getMesh().getNormals()){
        ofVec3f normalVector = (i * normalMatrix).normalize();
        finalMesh.addNormal(normalVector);
    }
}

//--------------------------------------------------------------
void ofApp::draw(){
    cam.begin();
            drawNormals(10.00);
    cam.end();
}

void ofApp::drawNormals(float size){
    for (int i = 0; i < finalMesh.getNumVertices(); ++i){
        ofVec3f vertex = finalMesh.getVertex(i);
        ofVec3f normal = finalMesh.getNormal(i);
        ofPushStyle();
        ofSetColor(255, 0, 255);
        ofDrawLine(vertex, vertex + size * normal);
        ofPopStyle();
    }
}

As you see in this screenshot, the normals of this vertical cylinder are wrong, they are always parallel to the y axis

P.S. This post is the following of another one, but the title of the previous one has nothing to do with what is now my current issue.