Whiteboard: Pen tool: How to use the color picker?

[barncro]

I can't get the color-picker tool to work on the whiteboard.  I can add custom colors using the palette provided under the Pen tools menu.  However, when I select the color-picker tool (also on the palette menu), I'm allowed to go through the motions of selecting a pixel on the screen, but no custom color is added to menu.  What am I missing?

[Zoom v6.5.0, Desktop App on a PC]