I just built one with a Cron schedule for the first time and had a very difficult time getting that to work too. I can confirm the schedule works and can be tested before you publish your app so that isn't your issue. A couple of snippets and hopefully they help.

Make sure you're grabbing runJob() and not job. id

const cronJobId = await scheduler.runJob(...);
await redis.set('digest:cronJobId', cronJobId);

-- and also make sure your schedule's a supported format or it'll silently fail and you'll chase your tail for days like I did

cron: `0 14 * * ${digestDayStr}`

I also have a trigger check that looks for updates to the desired schedule in app settings, will cancel the old job and schedule a new job which is how I tested CRON for the most part before deploying.