Try this code, you will reproduce the bug

 groupCommand->init(_globalZorder);
 renderer->addCommand(&groupCommand);
 renderer->pushGroup(_groupCommand.getRenderQueueID());
 //the following code is to add a quadCommand into the renderer
 sprite->draw(renderer, _modelViewTransform, dirty);

 renderer->popGroup();

in the final renderer, the sprite is not visible. and debug the code, we find a bug in the renderer, that if the renderQueue has only one command, it's execute will be ignored.