[rviz2-1] [ERROR] [1606145303.031461074] [rviz2]: FollowWaypoints action server is not available. Is the initial pose set?

[chcorbato]

Following the instructions in https://github.com/MROS-RobMoSys-ITP/MROS-Hands-On sometimes I get this error in the navigation2 terminal:

[rviz2-1] [ERROR] [1606145303.031461074] [rviz2]: FollowWaypoints action server is not available. Is the initial pose set?

And sending a Navigation2 Goal on RViz does not result in any observed behavior in the robot.
I am using:
mc_mros_reasoner: foxy_multi_model_files
Pilot-URJC: metacontrol-test-integration