BUG: rqt service caller didn't list node turtle1 & turtle2

[SpaceView]

Windows + ROS2-galactic ros2-galactic-20210616-windows-release-amd64.zip
I followed the instruction from
https://docs.ros.org/en/galactic/Tutorials/Turtlesim/Introducing-Turtlesim.html
to run turtlesim，

D:> ros2 run turtlesim turtlesim_node
D:> ros2 run turtlesim turtle_teleop_key
D:> rqt #(or rqt --force-discover)

unfortunately, when I use Plugins --> services --> Service Caller， I cannot find turtle1 (or turtle 2 after spawn) in the service combo box as described in 5.2. I can only find /clear /reset /kill /spawn services.

I use "ros2 topic list" and can only see the following 2 topics,
D:>ros2 topic list
/parameter_events
/rosout
D:>ros2 topic list --include-hidden-topics
/parameter_events
/rosout
D:>ros2 topic list -v
Published topics:

• /parameter_events [rcl_interfaces/msg/ParameterEvent] 1 publisher
• /rosout [rcl_interfaces/msg/Log] 1 publisher
  Subscribed topics:

However, if I running this example
https://docs.ros.org/en/galactic/Tutorials/Understanding-ROS2-Nodes.html
after "rqt" graphics windows appears, sometimes I can see all the nodes, including my_turtle, teleop_turtle, turtle1, turtlesim in the service combo box.

I also installed ros2-foxy (ros2-foxy-20220208-windows-release-amd64.zip), and I got the similar problems.

It seems the service caller is not stable. Any idea what is going on, and how can I debug this problem?

[JohnTailor]

I also thought I had the same issue, but at some point in time it just worked.

1. Make sure that in RQT you press refresh (left button next to "Service"), then when you need scroll (!!!) after clicking the down arrow at service.
2. If that does not work, spawn a turtle: Choose spawn command, change x to 5, change y to 5, change name to "turt99" and press "Call", now try to list the services again. In my case they just showed.