Dynamic approval in workmanagement project

[Dominic Peters]

Hey guys!

I'm trying to build a dynamic approval in a workmanagement project. I have an automation that created several subtasks based on a simple condition. I want that one of this tasks has to be approved by the assignee (i created a seperated issuetype for the approvals and Link it with the triggerIssue). The task is created but the approval is empty all the time.

from this site here 

Dynamic update the Approval in Jira Work Management projects | Jira | Atlassian Documentation

is a tutorial, but this did not work. If i do this like that i get an error message in automation log "The Customfield_XXXX with the name "Approvals" does not support the Operation "add". Supported Operations are: "set". But if i use "set" there appears the next error message after another try "The Function value must be a character string"

What does this mean? Has anyone an Idea?