Problems with Conversion Error on Person Fields on Site Workflows

I get the following Coercion Failed Error when trying to convert a Workflow Person Variable to "Display Names, Semicolon Delimited":

Interestingly enough, this DOESN'T happen if I am in a List Workflow and use the Person Field directly from the List.

I have an idea of how to get this to work, but it ain't pretty:

1. Copy PersonField to Text
2. Split the Text Field into many fields and store in a collection variable
3. Do a count on the Collection
4. Iterate through the collection use a Single Line Text Variable to store the current item
5. Set a Person Field Variable to the Single Line of Text
6. Use the Person Field to store Emails or Display Names