Writing Center - Instructor and Peer Review settings should be considered and set before starting a new class. If you change your settings after students have started working in the class, the effects can be confusing for existing students.
Any student who is working within a part of the workflow that is affected may experience a loss of work, or have additional work to do.
If you are teaching a class with rolling enrollment and need to make a change, the ideal time to do so is when all or most of your students are not in the Writing Center for that particular unit (either before they start or after they have moved on).
If you must make changes while there are active students, you should work with those active students individually to let them know that you are making changes, and see how it affects them. Some students can move on through without much difference, but others may need to be reset so they can start over.
No student will be blocked and any "lost" work will be due to a review requirement being eliminated.