Cannot update data points with quickquiver/quickscatter, but can for quiver/scatter

[GenevieveBuckley]

The markdown README file in ipyvolume shows a screencast example of a quiver plot being updated by directly altering the attributes quiver.x, quiver.y, etc.

I can't do the same thing for quickquiver() or quickscatter() plots. Is this expected behaviour?

Version numbers
Python 3.6
ipyvolume - 0.5.1
ipywidgets - 7.4.2
ipywebrtc - 0.4.3
pythreejs - 2.0.2
ipython - 7.5.0
Chrome (latest, up to date) - Version 74.0.3729.169 (Official Build) (64-bit)

Works

import numpy as np
import ipyvolume as ipv
x, y, z = np.random.random((3, 100))
figure = ipv.figure()
myplot = ipv.scatter(x, y, z)
ipv.show()

Then when I run this...

new_x, new_y, new_z = np.random.random((3, 100))
myplot.x = new_x
myplot.y = new_y
myplot.z = new_z

... all the points update on the plot.

Doesn't work

import numpy as np
import ipyvolume as ipv
x, y, z = np.random.random((3, 100))
myplot = ipv.quickscatter(x, y, z)
ipv.show()

Then when I run this...

new_x, new_y, new_z = np.random.random((3, 100))
myplot.x = new_x
myplot.y = new_y
myplot.z = new_z

... nothing happens to the plot.

I don't see any python errors.

Oddly there is a javascript error or warning for the first, working example, but NOT the second non-working example.

3three.js?v=20190527164443:294 THREE.InstancedBufferAttribute: The constructor now expects normalized as the third argument.

I do see a lot of javascript deprecation warnings, but I think they're irrelevant to this.