The CRON event is scheduled within the activation hook, and the handle for the job is:
pta_sus_cron_job
I like the plugin Crontrol for examining Cron events and rescheduling them or forcing them to run.
If you are not seeing that Cron function, then something may have prevented it from being set up properly when you first installed the plugin. So, you may want to first try simply deactivating it and then reactivating it, which should schedule the function again.
If that still doesn’t work, then perhaps there is some other plugin causing some weird conflict that is preventing the cron job from getting registered? Hard to say as it is working fine on my development server as well as my son’s school PTA web site.
If it still isn’t showing up after deactivating/reactivating the plugin, you could use that Crontrol plugin to add an hourly cron job, with the hook being: pta_sus_cron_job
and just leave the arguments set to none: []
Then see if it works.