Libgdx shaperenderer draws black instead of red after drawing a tilemap of modelinstances

Question

Hi I am using screens from libgdx and i am trying to create a battle scene which above all else includes a map. the map is simply an array of Tiles, each tile contains a ModelInstance of one of the various blocks i create. the map draws beautifully, however in my map i need to highlight the selected tile. again this works beautifully, except that the shaperenderer keeps drawing the lines black instead of any color i set. heres my screens render function:

@Override
public void render(float delta) {
    camController.update();
    pCam.update();
    Gdx.gl.glViewport(0, 0, Gdx.graphics.getWidth(),
            Gdx.graphics.getHeight());
    //Gdx.gl.glEnable(GL10.GL_LIGHTING | GL10.GL_GENERATE_MIPMAP
    //      | GL10.GL_BLEND);
    Gdx.gl.glClear(GL10.GL_COLOR_BUFFER_BIT | GL10.GL_DEPTH_BUFFER_BIT);
    Gdx.gl.glLineWidth(4);

    batch.begin(pCam);
    map.render(batch, env);
    batch.end();

    renderer.setProjectionMatrix(pCam.combined);
    renderer.begin(ShapeType.Line);
    renderer.setColor(Color.RED);
    map.highlightSelectedTile(renderer);
    renderer.end();
}

The glenable call was simply me trying various things in an attempt to solve this.

the maps render and highlight functions go like so:

public void render(ModelBatch batch, Environment env) {
    for (EncounterMapTile tile : tiles) {
        tile.render(batch, env);
    }
}
public void highlightSelectedTile(ShapeRenderer renderer) {
    if (selectedTile != null) {
        Vector3[] pos = selectedTile.getBounds().getCorners();
        renderer.box(pos[4].x, pos[4].y, pos[4].z + .1f, cellWidth,
                cellHeight, 0);
    }
}

and finally the mapTile's render:

public void render(ModelBatch batch, Environment env) {
    batch.render(instance, env);
}

so logically i can find nothing wrong with this. all the info ive dug through has suggested to make sure your not nesting renderer calls inside batch.begin/end and so forth. but honestly i cant seem to figure out why when using spritebatches this works, but when working in 3d with modelInstances, it doesnt save the color. I was under the impression the shaperenderer is completely separate from batches... help?