[ROS gz project template] Invalid frame ID passed to canTransform

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I'm getting these warnings in the terminal, running the ROS gz project template. Simulation works just fine, so why does these warnings show, and how can I fix the problems?

[rviz2-4] Warning: Invalid frame ID "diff_drive/chassis" passed to canTransform 
argument source_frame - frame does not exist
[rviz2-4]  at line 93 in ./src/buffer_core.cpp
[rviz2-4] Warning: Invalid frame ID "diff_drive/lidar_link" passed to canTransform 
argument source_frame - frame does not exist
[rviz2-4] at line 93 in ./src/buffer_core.cpp

Here is a screenshot from RViz, displaying the

and here is the "frame tree" from ros2 run tf2_tools view_frames

So basically the error complains that the frames under the "chassis" frame, are not connected the diff_drive/odom frame, just as shown in the tree. This corresponds with the links defined in the model.sdf in the description package, imported by the Gazebo example package in diff_drive.sdf.

Somehow a collection of the links in the included SDF file, are duplicated outside of the diff_drive/odom tree.

  <include merge="true">
    <uri>package://ros_gz_example_description/models/diff_drive</uri>
  </include>

I notice that the models in the model.sdf file and diff_drive.sdf file has the same model name (diff_drive). Can that be a source of misbehavior?