In System -> Scheduler details
There is an exclamation mark next to
CompatibilityPluginScheduler.JobRunnerKey.com.atlassian.jira.plugins.dvcs.scheduler.DvcsScheduler
and
com.thepluginpeople.jira.emq:PurgeAuditHistory
When I expand them it just says
Job runner key 'com.thepluginpeople.jira.emq:PurgeAuditHistory' is not registered