Print Task and secured Feature Layers (but not dynamic ones)

Discussion created by deepsheep on Jul 2, 2014
I've got a head scratcher here...  We're trying to get the Export Web Map print tasks to work.  It works fine for any non-secured service, and secured dynamic services, but a secured feature service dies with "Failed to create layer from service at <serviceurl>".

We're on 10.11 and I just applied all the patches this AM (which fixed the secured dynamic layers).
We're using Windows Auth.
The print task (and layers) are going through a proxy.
The secured print task and secured layers (both working and broken layers) are on the same machine.
If I change the layer from a feature to a dynamic, it will print fine.  However, that breaks some of our other custom tools, so it's not really an option.
Non-secure feature services print fine.
It fails the same way if I submit the JSON to the print service via the rest form.

I'm pretty sure the issue ISN'T with security at this point (if it was, changing the layer type shouldn't work), so I'm not sure what else to check out.