I've scanned the forum for this and haven't found anything on it. I'm also fairly new to the current ArcGIS Runtime, so be patient with me.
I'm trying to add a background to the text symbols I'm showing, but they don't show up, or else I'm doing it wrong (probably the latter). I tried a composite symbol, but that didn't do what I needed either.

There needs to be a dark background behind this, but no such luck.
Any suggestions would be greatly appreciated.