Variables can be added to list layout of any report when they are under the source table
KB0706864 - Create a list report with variable columns

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

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