Can't get "process milestones" to work

Hello,

I can't get the "Process Milestones" process to work. I can manually add a milestone to a student, but when I try to do it for many students simultaneously using "Process Milestones", I'm able to set the control parameters, and then run the process without any problems, but the log is always empty and no changes are made to the selected students. I've tried both with population selection and with student list, with the same result. I checked for milestones security and everything looks just fine. I'm looking at the Peoplebook section on process milestones and I can't figure out