On the 4 battery charging hub the light is yellow and it turns off after charging to only 50% It won't charge past 50%. Was there a firmware upgrade for Inspire 1 and P3 batteries?
With it plugged in power on the battery and see if that force it to start charging. Batteries that are more than 50% charged will sometime require a little help in starting them charging.
Rrotz, I ran into the same issue when charging my Inspire 1 batteries on Saturday. One of the batteries only charged 50%. DJI did release an update for the hub (which I installed). If you didn't install the update, you can download the "Charging Hub Upgrader" here.