While checking the Report for "Execution Attempt" we can notice that Names for the tasks might be missing for Managed Delivery policies, while it shows correct data for Patch and Quick delivery tasks.
During the localization process, while verifying task names for different languages, due to the missing value (no language) - the report would return an empty value.
The issue has been fixed in the ITMS 8.7 Release.
Meanwhile, the attached Stored procedure can be applied on the 8.6 RU3 release to resolve the issue.
To apply the provided Stored Procedure. Please backup your CMDB database or backup existing sp_SWM_SoftwareDeliveryExecutions. And then execute the attached SP in SQL Management Studio.