ROS Melodic, Gazebo 9. Ubuntu 18.04.

I'm running gazebo only and I've noticed this error.

Node::Advertise(): Error advertising a topic. Did you forget to start the discovery service?

This error occurs whenever I select an object(i.e. cylinder from the gazebo library) and scale/rotate/translate it and select it again. Any suggestions? I'm assuming that I don't need to run roscore since gazebo is a standalone application.