I think I have found a little bug. First of all sorry for my bad english.
Briefly, when I target a mob to select it the indicator above his head is yellow. You know, we can target a mob by clicking the space bar or the "z" key. Then, if we click another time the space bar/z key the indicator became red and now the player attack the mob. Here I found the "bug" or technical problem is better in this situation. While the player attack the mob the red indicator sometimes/often became yellow and the mob is not killed. This oblige me to click another time the space bar/z key to ensure that my character hit the last time the mob to kill him.
It isn't a very big problem, maybe a bit boring but not more than this. I hope I explained well enough.