arcgis desktop - Maplex issues with "vbnewline" in ArcMap

I'm trying to stack labels using an expression I wrote using VBScript.

I can get them to stack using "vbnewline" but it is a no go when using Maplex's label stacking options.

Using ArcGIS for Desktop Standard 10.3.1. The layer in question is a shapefile and not a geodatabase feature class. The label being used is a banner to call out the feature. I tried to "force split" using spaces in the label expression.