Symbol Source failure

A symbol package for a .NET 4.5.2 component is built on TFS and uploaded to a Proget feed.
Using Visual Studio 2013, I create a new solution for a console executable and add a reference to this package; I add a line of code with a breakpoint so I can test stepping into the component;
I hit debug; It downloads the PDB file correctly to the symbol cache;
Visual Studio prompts me to find the source code. It asks for the full path that was used when the package was built on the TFS server. But I don't have the source code on my laptop. I wanted to pull it from the Proget symbol server!

I checked the downloaded PDB with srctool -r. It lists all source files, using the path used on the build server.

Isn't Proget supposed to reindex the PDB file to tell it to obtain sources from the source server? That doesn't seem to be happening.

Can someone help me with this?

Product: ProGet
Version: 3.4.4

Is this a NuGet package you can send to us for testing? If not, a Fiddler trace of Visual Studio trying to access symbols would also be helpful. You can send either to support at inedo.com and we'll try to reproduce this.