Cannot use macro to update multiselect field!? Really!?

Cannot use macro to update multiselect field!? Really!?

Are macros unable to update multiselect fields? 

I am trying to configure new macros for my leads and contacts that will update a custom multiselect field I have created. The field does not appear on the list of fields available to configure. 

Am I missing something or are macros not able to update these fields? 

Thanks
Michael