In this scenario, in the analytics overview, the total amount of students or groups finished with the assignment is displayed incorrectly.
What happened?
Your students have finished all their reviews, but because in the setup of the assignment a higher amount of required reviews was set than eventually made by students, inconsistencies show.
For Peer Review and Group Member Evaluation a preferred learning activity is that all students in a group provide each other with a review. When group sizes differ, this causes some trouble with the analytics.
When setting up an assignment, you can set a fixed required amount of reviews as such to make sure all peers in one group review each other, see as well the set up manual for this. When there are groups of different sizes, you will still need to set a fixed amount of required reviews, causing that a higher amount of required reviews is set than eventually made by students.
The implication is that the system doesn't (yet) recognise that the groups are actually finished with all their reviews and therefore the overview you get is not trustworthy.