[Add Certificate...] hangs in Profile Manager 2 (Mountain Lion)

I just installed Mac OS X Server on Mountain Lion for the sole purpose of configuring a new network profile for my workplace. After configuring my system to enable Profile Manager, I launched the Profile Manager web interface, logged in, went to Device Groups, and created a new profile.

Settings are to include:

General (required): includes general info about the profile itself

Network: configure profile for both wired and wireless 802.1x authentication

Certificates: include two certificates to trust for authentication to the network.

I was able to easily configure General and Network. However, whenever/however I attempt to upload the required certificates, the browser window displays "Uploading <name of certificate file.cer>...", with the spinning indicator and does nothing else, regardless of how long I leave it alone.

Thoughts appreciated. Considered firewall, DNS, etc issues but haven't found anything that may be getting in the way.

Thanks.