Why is the "UID_RichMail" parameter empty in process "VI_ESS_PWOHelperPWO send mail to remind approver"?

Hi everyone,

In One Identity Manager v. 8.2.0 there's the default process "VI_ESS_PWOHelperPWO send mail to remind approver". In the Designer, inside Pre-script for generating, I can see by default: 

values("UID_RichMail") = $FK(UID_QERWorkingStep).UID_DialogRichMailReminder$

I wanted to try the process, to see how it's working. So from the Object Browser I generated the event REMIND on one object of the table PWOHelperPWO in order to start the process. Anyway, it didn't start. Looking at the log, this is what I've found:

2023-02-10 09:57:02 +00:00 - \JOB-SERVER-DEV - VI.JobService.JobComponents.MailComponent - f197de10-13c7-48a4-905d-ad5c03970874: Errors occurred
    [System.ArgumentNullException] Value cannot be null.
    Parameter name: idMail
       at StdioProcessor.StdioProcessor._Execute(Job job)
       at VI.JobService.JobComponents.MailComponent.Activate(String task)
       at VI.JobService.JobComponents.MailComponent._SendRichMail()
       at VI.Mail.MailComposer.<Compose>d__6.MoveNext()

In the QERWorkingStep table, all the values of the UID_DialogRichMailReminder column are NULL.

Why is that? What should I do?