Xendor, I will move this thread to the server’s community in order to get assistance on your question.
You should be able to remove the backplate support for the heatsink. I could not find any previous records about other customers using your heatsink with this board model.
After this has been resolved with Intel Support I can shed some light on this.
As it turns out I was sold the rack version of the S1200BTS, which has a backplate glued onto the backside of the board.
Although it is not recommended by Intel to try and remove the backside it is possible if you are careful.
The heatsink fits nicely to the board.
Thanks for your help.