How to enable Filter by Approvers
To enable filtering by the Approvers field, a search template must be selected in Jira field settings. If this is not configured, the field cannot be added as an additional filter in Advanced requests Report.
You can adjust the field settings in Jira by navigating to:
System → Work items → Fields → select the field → click the three dots at the end of the row → Edit.
The list of users in the Approvers filter consists of all users from the current Service Management project.