Was this template created before or after the setting 7.6 was enabled?
It sounds like the template might've been created before this setting was enabled and the template needs to be updated.
To update the template,
1. create a project with the same template
2. enable the setting 'actual effort updated from timesheets' on the lowest leaf work-item where effort will be reported
3. in the work plan panel, click 'Misc' and click 'Save as Template', then select 'override existing..' and select the same template to override with changes
If this is not the issue, please open up a support case with us so we can have a closer look at what's going on.