Configurator 1.4.2 (370). OS X 10.9
I have 20 iPads that I'm managing with Configurator. I have purchased 20 licenses each for two apps through the Volume Purchase Program. I have Prepared tablets with no trouble. On the Supervise panel I assign the paid app to the devices and apply. 19/20 ipads complete successfully.
One iPad completes with an error for both apps: Unable to redeem code for "App Name". There are no codes left to redeem.
Looking at the licenses for each app it clearly says there is one remaining code available.