Black Balance taking forever. What is happening?
 

My FS700 just received the 4k/raw firmware upgrade (3.10). Normally, per the manual, I typically black balance when I change lenses. In this instance, following an upgrade, I thought do to the same.

In HD mode (not 4k), where black balance is available, I had an ENG lens mounted through a few adapters. Prior to the upgrade, black balancing took about 30 seconds. Now, I waited around 10 minutes while the screen showed "Executing." Out of impatience, I turned off the camera -- I actually had to remove the battery and an external power source -- and the camera turned on again with normal function.

Any ideas why black balancing would take a long time or get 'stuck'? I've seen anecdotal evidence around the web about having to use a Sony lens, but I know that isn't the case, since I black balanced on a variety of lenses, including my ENG lens.