Find Image on Screen using Clipboard Image?

I've attempted to use Peter's suggested actions and AppleScript but I'm getting mixed results.

Most of the time an image is not found (at least 95% of the time).

Things I've tried:
• Adjusting the Fuzz to various values from 1 to 100.
• Adjusting the Fuzz to values up to 1000 - it tends to work better but still fails often.
• Using newly created clipboards (in case overwriting a clipboard is an issue)
• Using different names for the file being written to (in case there are silent overwrite warnings)
• Deleting variables used
• Ensuring my capture area is unique
• Changing the image format to PNG
• Trying different values for ScreenAreaType

My script is basically the same as Peter's with a few modifications picked from other replies and my intent to capture the image into the clipboard:

Keyboard Maestro Actions.kmactions (5.3 KB)

What could be going on here?