Logged In User as Default User in Custom User Picker Field [Single] not working Jira 8.20.0

[Teja]

Hi Team,

We have customization in our Jira server instance

We are setting 'Logged In User' as Default User in Custom User Picker Field [Single] when doing the transition button.

It was working fine when Jira 8.7.1 version, after the Jira upgrade 8.20.2 it stops working now.

We use javascript in field configuration 

if($('#issue-workflow-transition-submit').val() =='Qualification Approval'){ //Fetch currentUser ID who is doing Qualification Approval transition
epicQulificationApprover = document.getElementById('customfield_13006'); //Qualification Complete Approver 'customfield_13006'
epicQulificationApprover.value = AJS.params.loggedInUser; 
}

Before upgrade

After upgrade

Thanks in advance