Can’t get Shift K OR Ctrl X to work in vertex paint

@Martin Bergwerf       “When I said try it on a default Cube, I meant, try it on a default Cube.”

So, Martin. I’m unclear. Are you saying I should try it on a default cube?   Ha. Yes, I tried it on a default cube and it works fine. I’ll check that I’m in material preview mode and that the vertex color (Attribute Node) is connected to the material.  Thanks for you input.

@Martin Bergwerf     Your remark didn’t offend me. I just wanted to jab you a bit for fun. If you read some of my descriptions from my gallery, you’ll note that I sometimes fancy myself a comedian (although some wouldn’t agree – my wife, for one). You are correct. I didn’t make myself clear with the “Tried it on a cube with one sphere inset” comment. I actually tried it with just the default cube but was confused because it turned the entire cube black. You were very helpful and I appreciate it. As for your “trick”, it’s a good one. Sometimes just going back to the very basic cube and trying whatever one needed to try is an excellent way to make sure the problem isn’t with the shortcut, software, or the computer itself. Bottom line, thanks again for your input.