Trouble Binding a Mashup Name to "TargetMashup" property on Navigation Function

Here is the situation:

• I'm using a collection widget which displays a group of mashups for the user to select between (collection because different users will have different options)
• The repeated mashup in the collection contains the mashup name (in text) and a button to "navigate" to that mashup. This button triggers a Navigation function on the contained mashup.
• The contained mashup has a mashup parameter for the Mashup Name to navigate to, and I've bound that parameter to the "TargetMashup" property in the navigation function.
• Clicking the button in the contained mashup of the collection is not sending me to the navigated page. 

What I've checked so far:

• Mashup trace is showing the Navigation function as "ServiceInvoked" but it is never completed. (screenshot attached showing the only two lines in mashup trace after clicking the button to navigate)
• I've bound the Mashup Name mashup parameter to the "MissingMashupMessage" property of the Navigation function, and the mashup name appears in the message, so I know the parameter is there, and is being bound to the Navigation function - it just isn't being recognized as the TargetMashup. (the screenshot attached shows the bindings to both properties, but removing it from the missingmashupmessage does not effect the result...)
• Yes, the mashup names being passed match EXACTLY to existing mashups.

Is this a defect/bug? Am I missing a step? Any and all help is appreciated!