The new version of the bug: when I walk sometimes suggest that to sink in water for a few seconds.
thus to this bug happens when I walk on the ground floor,
I found:
it's normal
https://postimg.org/image/lqx2z68pp/
when I hold spear and attack shark, after I attack sharp spear in normal
https://postimg.org/image/wecxswnbb/
I can no longer attack with this spear, then I have to restart the game. but the bug reappears