I am having an issue with trying to update a multi-select choice field on my context item via the Update item action.  I have created a custom task form, to which I have added a multi-select choice field, and I save the value of the choice field to a variable for update to a corresponding field on my list item, through the workflow Update item action.  However, after the update, though I am seeing the updated field value(s) on the list view, I do not see them in my item form, (which is a Nintex form).  Is there some sort of magic formula for updating multi-select choice field via workflow, so that the selected values are visible on the form?  Incidentally, if I choose only one item in the multi-select values, the one selection is displayed in my form, this only fails with multiple selections.