In order to troubleshoot the issue, you can follow the steps below:
1) Confirm that "ROS_DOMAIN_ID" is set to 112 from both the MATLAB R2022b Command Window and the ROS 2 Foxy command prompt.
In particular, using the ROS 2 Foxy command prompt, set "ROS_DOMAIN_ID" outside MATLAB using the command
set ROS_DOMAIN_ID=112
and then check that the ID is correctly set using the command
echo %ROS_DOMAIN_ID%
Then, to see the list of topics in the ROS 2 Foxy command prompt, execute the command
ros2 topic list
a few times in case you do not see topics for the first time on that particular domain ID.
2) If the topic list still does not contain the topic of interest "my_topic", execute the following commands in the ROS 2 Foxy command prompt
ros2 daemon stop
ros2 topic list
to see if the topic appears in the list.
3) If the topic list still does not contain the topic of interest "my_topic", delete all possible files from the folder where the ROS 2 Fast-DDS specific cache files are located. Ignore the ones that cannot be deleted, as they are locked by the ROS 2 node running in MATLAB R2022b.
Then, in the ROS 2 Foxy command prompt execute the commands below
ros2 daemon stop
ros2 topic list
to see if the topic appears in the list.
