MathCAD v15.0 Excel Component Summation Character

I have a component excel sheet embedded in a MathCAD sheet, in which I have a summation character ∑ (Unicode (hex) character code 2211).

In the MathCAD sheet, the summation character is displayed as a question mark, ?, however when I click to edit the excel component it reverts to the correct ∑ display. It also prints out as a question mark.

Anyone got workarounds or suggestions?

(I am on 64-bit Win 7 and using Mathcad 15.0 (15.0.0.436 [006041742]))

Thanks