Hi Jeff:
In your case, if you need to show all 48,000 features on the map, you should add the root map service, rather than the individual layer within the map service. Or if you need the client-side functionality (pop-ups, interactive table, symbology configuration), then you may want to consider separating out your dataset into more digestable chunks.
The basic problem is that this is simply too many data points for the browser to render with a rich visualization (i.e. high fidelity mapping). At the current release, the product is not able to retrieve features that are just within in the current extent. So the main options that occur to me are (a) use the map service, which the browser can easily handle because the service just returns a few image tiles for each map extent, or (b) break up your dataset into finer-grained subsets.
Hope this helps.