@MojangSupport
So we had been hit with the infamous "Villagers despawned with no fault" bug. All were name-tagged, max trade, super lit and safe, walled environment with beds and work spaces, and even an iron golem. Realm owner reset to a previous save, and they're still gone???
We apologize for the inconvenience, but this is currently a known issue. The team is currently working on a fix that we hope to have out to everyone as soon as possible. Thank you for your patience while we work on the solution!