Simplified Hours Report for Portfolio, Program, and Projects

I'm looking at the report delivery overview (Formatting section) here:

https://experienceleague.adobe.com/docs/workfront/using/reporting/reports/create-manage-reports/set-up-report-deliveries.html?lang=en

The first line says "You always receive the default tab of a report when a report is sent or scheduled for a delivery, unless the report has a special view." 

On the report settings page:

https://experienceleague.adobe.com/docs/workfront/using/reporting/reports/create-manage-reports/edit-report-settings.html?lang=en

it says: "When the Report loads, show the:

Select the default tab that is displayed for all users when the report loads."

Both these together seem to indicate that if you have Summary selected as the default tab, then it should be mailing you the contents of the Summary tab. You could submit a case with Adobe's Support if you're authorized to do so, and ask them to investigate further.

As a workaround, you might consider using a matrix report. Just make sure your hours report is very simple and only contains the columns you want to show up in the matrix report, otherwise it will drag in the extra cost information, etc.