Hi Greydon,
Thanks so much for responding! Sadly my school is not very engaged with their internal helpdesk, though I have submitted a ticket and shall see.
The students are all in the same section. I assigned the peer reviews manually, in groups of three, and the students who cannot see and access theirs are dispersed among the groups randomly. Most have been seeking to access the per reviews from the home page as the other students were able to, so the link may be helpful. I did double-check that none were left behind, all were fully assigned, and I clicked the notify bell again, and students reported being notified, yet not having access when they clicked through into the system. The access date for the assignment is in the past, and I also played around with the due date to see if making it in the past or future helped, it did not, so the due date is set in the future. I will ask them for screenshots if this link or time doesn't resolve the issue.
Thanks again.