Thank you for posting your question. What are mentoning is being caused by the same issue as this document Manual scans work, scheduled scans fail: Scheduler Credential . The console scheduler credential must have local adminstrative rights and be the currently logged on user because the Microsoft task scheduler uses the logged in credentials to encrypt and decrypt scheduled tasks. Since we use the Microsoft Task scheduler we require that the scheduler credential you set be the logged in user with local adminstrator rights.
It is also important to note, that this credential only deals with the Microsoft Task scheduler and is not used for the target machines you may be scanning or deploying to.