There is a change in behaviour from CA PPM 15.1 to 15.4, where the Process Logs are no longer showing all information.
Navigate to in CA PPM to Administration, Processes, Initiated, Show All.
It is now mandatory to enter a Final Date in order to get data.
There has been a change in functionality to avoid slow performance when a Process Job is executed with no dates specified.
The change is 'Finish Data To' which now when no date is specified, has a default which is 'Start of Previous Quarter'
Enter in a final date to get the expected range.