Hi Thomas,
The problem can be related to authorization relevant tick on characteristic. To understand that, go to rsd1 and display that characteristic. Then go to Business Explorer tab. You can find Authorizationrelevant checkbox.
To test that, I will suggest you to compare with a different characteristic without Authorization relevant tick. If in bex query, one of the characteristic(without authorization tick) can be restricted with exclusion and one of the characteristic(with authorization tick) cannot be restricted with exclusion you can understand that the problem is caused by the authorization tick.
Best Regards,
Muhammed