Issue with "Periodic Alert Scheduler"

EBS:12.2.4

Expected behavior:

When you start the Periodic Alert Scheduler, Oracle Alert submits it as a concurrent request to the concurrent manager to run every 24 hours at 12 AM.

Every time the Periodic Alert Scheduler runs, it submits a request to the concurrent manager to be run again the next day at 12 AM.

(https://docs.oracle.com/cd/E51111_01/current/acrobat/122alrug.pdf)

So I expect once I activate the "Periodic Alert Scheduler", it is run once, then scheduled next day at 12AM everyday.

And I have confirmed this behavior in our internal environment.

My customers problem is that when they Activate the Periodic Alert Scheduler it is not scheduling to run EACH day but just ONCE. It will schedule other jobs as expected, there is NO last request for the Periodic Alert Scheduler to run again.