Service Bus Message Can Be Peeked But Not Received From One Specific Computer

I have a C# dotnet application that sends and receives messages through service bus topics+subscriptions using Microsoft's messaging client SDK v3.  On one customer's server I can execute a Peek command on a topic subscription and see there is a message available to receive.  However, when attempting to Receive the message, the operation returns null after timing out, as if there is no message available.  

I've written a test app to reproduce this and can verify the Receive executes successfully from my a different computer in the customer's office but will *not* Receive from this one specific system.

I would greatly appreciate any guidance you can provide on what I might look for to explain this isolated behavior and things I might try to resolve the problem?

Thanks!