Troubleshooting Oban Library in Elixir Phoenix (Missing Jobs)

I am using Oban library in my elixir phoenix web application.

{:oban, "~> 2.7.1"}

I have three worker on this service. Other service have difference workers too using same database.

{"10 18 * * *", PopulateWorker, priority: 1},

{"10 19 * * *", HouseCleaningWorker},

{"20 19 * * *", FileCleanUpWorker}

I notice that some unexpected behaviour with this library that I didn’t understand about.

Expected: This three workers should run every day at desired time.

Actual: HouseCleaningWorker is not run I never see data about this data in oban_jobs table for almost 1 week. After sometimes its working again.
I found some clue on Documentation. But I don’t understand Worker Node & Web Node that write in the documentation.

That’s why I still can’t find our the real problem.