I was working on another project and thought I was done until I tested the drag and drop capability (following a code example) and it failed to work as expected.

I was working on another project and thought I was done until I tested the drag and drop capability (following a code example) and it failed to work as expected.
I created a simple WPF .net8 project to test drag and drop, and it fails to work as well.
Any know the secret to making this work?