To reproduce: Start a few sessions of bash, fork something from one of the shells under a fork observer. The event shows up on all the process traces rather than just the one that forked.
I cannot replicate, is this showing up say Bash PID 1234 and Bash PID 3456 in two seperate eventviewers?
Does not happen anymore. Only the eventviewer of the process where the events occured show those events now.