RESTLet working in developer sandbox but returning blank on production instance

Hi, I have created a very simple restlet used to GET data.  This works fine on my developer sandbox to get the requested records (this is doing a simple search only on entityID for contacts).

It returns all records perfectly on my sandbox.

I do not control the deployment or setup of the RESTlet on the production box (for one of our customers).  It seems like it was setup correctly because the REST URL works and the Auth works (if I enter incorrect authorization it gives expected error).

But when I try to make the GET with this URL it seems to work but spits out nothing as the response.  Just a blank JSON response, no errors or anything,  Is it possible there is an internel error that just isn't being outputted?  I have also tested this with the simplest get record function that simply takes the id and looks up a contact.  Again it works on my sandbox and returns nothing on the production instance.