Offline tile server with mapbox layers

I am trying to use mapbox layers to display map tiles from a locally hosted tile server.

The tiles display when using this example:

However, when I replace that URL with my local tile server url, all I get is a white background and no map.

When i navigate to the URL for the tile server the tiles are there. Any ideas?

Have you tried toggling through the source types?

Type: enumerated , one of ( "geojson" | "vector" | "raster" | "image" )

Also note:

Parent: layout.mapbox.layers[]
Type: number or categorical coordinate string
Sets the source data for this layer (mapbox.layer.source). When `sourcetype` is set to "geojson", 
`source` can be a URL to a GeoJSON or a GeoJSON object. When `sourcetype` is set to "vector" 
or "raster", `source` can be a URL or an array of tile URLs. When `sourcetype` is set to "image", 
`source` can be a URL to an image.