Mixer Pad 'Sample Multiple Colors' Eye Dropper Does Not Work For Oil Brush

Using Mac with Painter 2020.  Brush is Oils / Fine Soft Brush.

I am using an image in my mixer pad and have recently used this same mixer pad image to paint with.  I was able to sample color with the 'Sample Multiple Colors' for this painting, but now this does not work.  I have shut down / restarted the app, but this did not help.

I have just verified that NO brush will sample paint with this eye dropper.

Any help will be appreciated.