Variables can be added to list layout of any report when they are under the source table
[code]<a href='https://hi.service-now.com/kb_view.do?sys_kb_id=87bf713edb9027c4d3c92926ca961964'>KB0706864 - Create a list report with variable columns</a>[/code]

However, this action isn't possible when the variables are under an extended field/table

1. Navigate to Reports > Create New
2. Enter
   Source Type: table
   Table: sysapproval_approver
   click Next
3. Select 'List' type report and click Next
4. Click 'Choose Columns'
5. Select Approval for [+] -> Requested Item [ catalog task ] [+] -> variables [+] -> select "New Email Account" > select "Preferred Email address" and click OK
6. Click Run
   
   Actual behavior: List layout doesn't get updated
   Expected behavior: 'Preferred Email address' should be added to the list layout

This issue is under review. To receive notifications when more information is available, subscribe to this Known Error article by clicking the Subscribe button at the top right of the article. If you are able to upgrade, review the Fixed In field to determine whether any versions have a permanent fix.