After a restart the Last changes history becomes empty. This is explained by following comment on JENKINS-49368:

https://github.com/jenkinsci/last-changes-plugin/commit/0cb6083a31b207099c5400e4f4a93bee8510f3a5 will not work correctly after the Jenkins restart. The class has no readResolve() resolution, so the value will be null when you save new jobs and reload them from the disk. It will cause NPEs in methods like getLastChangesBuilds().

getLastChangesBuilds() is what we use to create the history page.

Note that after a job run the history is restored.