For 3d vectors, tip is not getting oriented in proper direction.

I'm having a problem with creating 3D vectors. the tips are not getting oriented in correct direction. so it looks like the tip of the vector is broken. I'm using the above code. I've just started learning manim. so can anybody help me with this. I tried issue#774 but it didn't work for me.

I'm using this code :

```
from manimlib.imports import *

class vectors(VectorScene,ThreeDScene):
def construct(self):
v1=Vector(np.array([1,0,0]),color=RED)
v2=Vector(np.array([0,1,0]),color=BLUE)
v3=Vector(np.array([0,0,1]),color=GREEN)
v4=Vector(np.array([1,1,1]),color=YELLOW)
vec=VGroup(v1,v2,v3,v4)
self.set_camera_orientation(phi=PI/3,theta=-PI/2,distance=6)
self.begin_ambient_camera_rotation(0.6)
self.play(ShowCreation(vec))
self.wait(10)

```