I picked up 4 Auxiliary Batteries for 4 of my skills. I put them all in one slot on each skill but only the first one I placed in has worked. The first one went on Hive and the skill power went up by the battery number as expected. I put the other 3 on their relevant skills and no change to the skill power at all.

Is there a limit to one battery at a time? Or is this another bug?