A friend and I noticed that 'bumping' into each other whilst cloaked would sometimes cause us to lose all nanosuit energy. It seemed to be that the one moving/moving most quickly kept their energy, whereas the person not moving so quickly/standing still would lose energy. Happened 4 or 5 times in a few games where we were trying to test whilst still playing.
Yup. Its not just bumping in to players either. It also happens at random times, although to me seems to be on stairs or something similar. Maybe he stubs his toe?