title: 3D scatter points don't show on Plotly when I set marker size or opacity
body: <p>I have plotted a 3D scatter graph with an extra dimension of values. I tried to distinguish these by color but some of the points were close enough to block others. I thought I could solve this problem by making the higher value points larger or more opaque. The problem was when I set the marker dict size parameter to the array of values after I had normalized them, the points on the graph disappeared. In the case of opacity, I got an error. Below, I have included my code for normalizing and plotting. The points also disappear if I set the opacity to a fixed number like 0.8. What is the reason for this?</p>
  
  <p>I have a data frame called <code>stacked</code>(column headings are 'Y AXIS', 'X AXIS', 'INTENSITY' ,'Z AXIS').  I normalized with the lines below.</p>
  
  <pre class="lang-py prettyprint-override"><code>maxi = stacked['INTENSITY'].max()
  mini = stacked['INTENSITY'].min()
  
  norms = []
  for i in stacked['INTENSITY']:
      norm = float((i-mini)/(maxi-mini)) # multiplied by 12 for size
      print(norm)
      norms.append(norm)
  
  stacked['INTENSITY'] = norms  
  </code></pre>
  
  <pre class="lang-py prettyprint-override"><code>import plotly.graph_objects as go
  import numpy as np
  
  fig = go.Figure(data=[go.Scatter3d(
      x=stacked['X AXIS'],
      y=stacked['Y AXIS'],
      z=stacked['Z AXIS'],
      mode='markers',
      marker=dict(
      opacity = stacked['INTENSITY'] # size = stacked['INTENSITY']           
  )])
  
  fig.show()
  </code></pre>
  
  <p>I get this error.</p>
  
  <pre><code>ValueError: 
      Invalid value of type 'pandas.core.series.Series' received for the 'opacity' property of scatter3d.marker
          Received value: 0      0.038302
  </code></pre>