Dynamic reconfigure is blocking other plugins in ROS2

[jurajObradovic]

Running Dynamic Reconfigure in parallel with other rqt plugin blocks other plugin subscribers.

I was unable to use Dynamic Reconfigure in parallel with my custom rqt plugin. When clicking on the Dynamic Reconfigure plugin my subscriber callback function will stop being called.
To eliminate my custom plugin as a source of the issue I tested with the talker-listener example from ROS documentation and the topic monitor plugin in place of my custom plugin. The issue persists. If you try to use Dynamic Reconfigure while visualizing the topic on a Topic Monitor the topic will freeze on the last value.

ROS2 version used is Galactic.

How to reproduce:
1. Follow the tutorial on how to write simple subscriber in ROS2 https://docs.ros.org/en/galactic/Tutorials/Beginner-Client-Libraries/Writing-A-Simple-Cpp-Publisher-And-Subscriber.html
2. Run talker node and rqt_gui in parallel.
3. In rqt_gui open Topic Monitor and enable topic /topic in Topic Monitor, you should be able to see messages coming from the talker node.
4. Open Dynamic Reconfigure in same rqt_gui (Plugins -> Configuration -> Dynamic Reconfigure). If you select any node in the list /topic messages will stop arriving at Topic Monitor.