Why is my MessageToMessage Encoder not sending data? (Netty 4)

Question

    @Override
protected void encode(ChannelHandlerContext ctx, ServerEvent msg, List<Object> out) throws Exception
{
    ByteBuf data = ctx.alloc().buffer();
    msg.encode(data);
    out.add(data);
}

The above method lives inside of a MessageToMessage encoder. The server event simply takes a Bytebuf and writes data in the appropriate order for the event.

My client is never receiving this message. I have this encoder in my pipeline and I hit my breakpoints inside of this handler. What am I doing wrong or missing?