Variables of an extended field can't be added to the list layout of a report

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

After carefully considering the severity and frequency of this problem and the risk of attempting a fix, it has been decided to not address this issue in any current or future releases. We do not make these decisions lightly, and we apologize for any inconvenience.