Apologies, I searched for "Ballista" not crossbow.
Besides, I do not see how this was related to chunk performance, as it was being reproduced solidly as described.
I just died against all of these guys and they did not turn invisible: http://i.imgur.com/WjERVmE.png
For what i've seen, not a duplicate, only skeletons turned invisible.
This bug is happening again in 1.14.3