Thank you for your reply, Ian.
In regards to why dragging the "DRIVER VALUE" icon to the Background area produces no results, yes, I also suspect this is a bug with BI4.0 SP8.3.
I also suspect that removing the "Measure" group may resolve this issue, since the group only contains one measure. Do you know how I can remove the "Measure" group?:
Thanks for your help,
Michael