Martin,
Thanks for the advice. It's been of help when looking into this.
I spent most of Friday looking at the indexes on the tables in this query but they all seem fine.
I then took a real shot in the dark and recompiled the SSMBUSRELTABLE in my UAT environment. After a restart of the AX application I found the filter worked instantly. I then did this in my production environment over the weekend and got the same result. Do you have any idea how this would have made any difference?
Regards
Paul