Here are the answers to your questions about the bulk rating :
1. The bulk rating will affect the "user competency", not the "user course competency". If the competencies are linked to courses, the course competencies will still be not rated, but the user competency (at the learning plan level) will be rated.
2. For the cron job, it creates an "ad hoc" task, it is not a "scheduled" task. So it usually runs as soon as possible. Do you have some error logs you can look to see if there has been a php error or something? You can also check if some users were rated and not others... A rating and an evidence should be added for each user, and there should also be some event logs.
You can also see if the job has been executed by going back to the bulk rating page. When the job is not executed yet you have a "Evaluation is in progress" warning on the top of the page. If there is no warning, the job has been executed (it at least tried to do something...)
It is also important to know that, by default, the students who are already rated are not impacted. You can force their ratings with the "Force rating of users already rated" option.