I have built the 60198 Cargo Train and added a set of PU LED lights to port B with the train drive motor connected on port A (of the 2 port PU hub).
I have set up a profile with a slider controlling the drive on port A and a button controlling the lights on port B. Port A is working fine but I have discovered that once you have run the profile once, you have to exit the SBrick app completely and relaunch it before the lights on port B will again work. This can be most easily shown if you go into the test part and select port B, the lights will initially come on, but if you then attempt to repeat the test they will not work until you exit the app and relaunch it.
Note I am using the Android app (v4.8 update 0) running on Android 11.