Hi Paul,
Thank you for testing my problem. At the beginning I thought that background job saves the parameters for the variant and uses the initial settings - even if the variant has been changed. However
I have checked this on a very simple ABAP report and background job rereads the contents of the variant.
I have one quite sophisticated z-report for which this rule is not true (variant is not reread) so the problem is more complex but generally background job rereads variant's settings.
Thank you for your answer and your support.
Best regards,
Karl
PS. I use ECC 6.0