Dunning Email Sending Queue is empty after the release of Customer Dunning WF Scheduler

Dear Community,

Could you please, help with the below question.

I am running the Dunning E-mail sending queue for the first time and after setting up a dunning procedure, with Customer level evaluation criteria, schedule is manual and respective templates and 3 dunning levels have been assigned. Customer master data of a test Customer has been updated with the dunning procedure, dunning manager and recipient.

I have executed the Customer Dunning WS Scheduler, as an admin in a testing release status.  The Dunning  e-mails sending queue is empty.

Please, advise what to be checked in order to make the process workable?

Thanks in advance.

Kind Regards,

Iveta