Analysis for Office: Changing text of # "Not assigned" to SPACE

Hello,

I have an issue in Analysis for Office: The text of a member is shown as "#" although I defined the text in the master data of the infoobject with a blank value.
This is how it looks in AO with setting "show key and text":

And this is how it is defined in the infoobject:

In BEx Analyzer a blank text is shown, but in AO the text "#" is shown. What can I do to get no text in my crosstab?

Thanks in advance.

Regards,
Yvonne