Custom Mixer Brushes lose presets when Photoshop CS6 is restarted

Dear Adobe Customer Care Team;

I wasn't able to reply to this case within the allotted 24 hours, but I've done the suggested resets: Reset Tool, Reset Brushes, and Reset Preferences.

The issue was not resolved.

When I first sample an image for a custom mixer brush, everything works as expected. I can change the various settings in the brush panel (size, spacing, scatter, etc) and paint away. However, when I close Photoshop CS6, relaunch it, and select my previously saved custom mixer brush, it works until I make any changes in the brushes panel. At that point, the image loaded in the brush is lost. To get the brush panel settings to work again, I have to resample the image. Work invested to create the original brush image then has to be redone.

Do you have additional suggestions?

Thanks for your help!