Hi Bernhard,
I tried the first and third of your options, but there are no messages, and re-activating did not help. One thing I did find that was interesting is that when the query is run with the product hierarchy active and this being the only character in the report - it returns data not found. But if I then filter on the second node of the heirarchy - it returns data and works..... most annoying 
so I am not sure where to go from here.
Denise