While I and a couple of randoms were fighting Vanaduke. Phase 2 of the fight was upon us and I picked up a water ball to be thrown the instant phase 2 started. When Vana's mask popped-off and I threw my water ball, the ball just wouldn't throw and instead floated where I intended to throw it for the rest of the fight. My teammate, Vanaducks, picked up one of the other water orbs to throw it, but the same thing happened to him. Luckily the last 2 water balls weren't acting this way and we managed to finish the fight.

I am not sure if it'll help pin-point the bug, but I had 1 bar when I threw my water ball and Vanaducks had 2 bars when he threw his.

The Imgur-link I provided is of 2 screenshots, one of the first time it happened and the other of the post-boss fight showing all off the water balls.

https://imgur.com/a/L6VJU