Nicky,
Check that their EPM Member Selector for that particular dimension is not set to Description. You likely have yours set to ID - Description, which is why yours works.
You can get there by going to the Context, clicking the drop-down for the particular dimension of interest, and then Select Other Members. Then, you can click on the drop-down immediately to the right of the icon that looks like a notepad and select ID - Description.
Let me know if this resolves your issue.
Jeff