ros2 topic list only sometimes showing topics

I'm using foxy on Ubuntu 20.04. With the help of @altineller on this and the other issue I was able to get it to work. Thanks a lot for that =) Namely I changed the following:

DEV variable in entrypoint.sh script of the agent to what ls /dev/serial/by-id/* gave me
edited docker-compose.yml and added privileged: true to agent service

When I now do a docker-compose up --build I see the agent starting up and data being transmitted, e.g.:

stiot_agent_1    | [1617786788.116564] debug    | SerialAgentLinux.cpp | send_message             | [** <<SER>> **]        | client_key: 0x5B89F2CA, len: 13, data: 
stiot_agent_1    | 0000: 81 00 00 00 0A 01 05 00 23 0D 00 00 80
stiot_agent_1    | [1617786788.117852] debug    | SerialAgentLinux.cpp | recv_message             | [==>> SER <<==]        | client_key: 0x5B89F2CA, len: 24, data: 
stiot_agent_1    | 0000: 81 80 23 0D 07 01 10 00 0D 2E 00 15 39 B4 48 3D 4C 37 09 BE 96 43 1F 41
stiot_agent_1    | [1617786788.117904] debug    | DataWriter.cpp     | write                    | [** <<DDS>> **]        | client_key: 0x00000001, len: 12, data: 
stiot_agent_1    | 0000: 39 B4 48 3D 4C 37 09 BE 96 43 1F 41
stiot_agent_1    | [1617786788.117950] debug    | SerialAgentLinux.cpp | send_message             | [** <<SER>> **]        | client_key: 0x5B89F2CA, len: 13, data: 
stiot_agent_1    | 0000: 81 00 00 00 0A 01 05 00 24 0D 00 00 80
stiot_agent_1    | [1617786788.119352] debug    | SerialAgentLinux.cpp | recv_message             | [==>> SER <<==]        |

however

somtimes the topics aren't listed when I look into the agent container with docker exec -it micro-ros_sensors_demo_stiot_agent_1 bash and do a ros2 topic list and rqt obviously doesn't start up (as it is waiting for the topics to be present)
sometimes the topics are present in the agent container, rqt starts up but shows not data. The topics aren't present in the rqt container
sometimes the topics are present in both containers, rqt starts up, but doesn't show data AND no legend at all (like /sensors/imu//x), restarting the board via the reset button does not help.
sometimes the topics are present in both containers, rqt starts up, but doesn't show data BUT the legend is there. A simple press of the reset button on the board and data s coming in.
sometimes everything works, rqt starts up and shows data

All I'm doing between two runs with different outcomes is CTRL + c to stop the containers, wait for them to stop and then pressing the restart button on the board and doing a docker-compose up --build again.

While writing this I noticed, that I can do the following to get it to work more reliable.

After doing the changes described above and rebuilding the containers Ido a docker-compose up -d
If rqt doesn't start up press reset button on board and wait for rqt to show up
If rqt starts up but doesn't show data just close rqt and do a docker-compose up -d again

I can live with this behavior, especially because it's just a demo, but wanted to leave this here so others may struggle less. Regards

micro-ROS / micro-ROS_sensors_demo

ros2 topic list only sometimes showing topics #8

however