Can't install configuration profile using iPhone Config Utility 3.5 and iPad iOS 5.1

Sorry for the long title, but...

I had a certificate expire in my configuration profile (that allows access to the Enterprise WiFi network). In the past, that means I go fetch a new certificate, install it into the configuration profile, attach the device to the computer via USB, and download that to the device. It's all good.

With iCU 3.5 and iOS 5.1, that all works fine until the last step. I hit the install button - nothing happens. Zilch. Nada, Zero. I happen to be a developer as well, so I have Xcode open and am watching the device console. Absolutely nothing happens on the device console.

What am I doing wrong? I can't believe that this is broken, and if it is broken I'm the first person to trip on it, so what's up?

(I did workaround this problem by exporting and sharing the configuration via email to the device and installing it from the attachment. That part still seems to work, and the profile itself also seems to work. The problem seems to be with iCU and downloading profiles.)

Thanks for your help.