Custom keyboard command not working (Mac)

Hi,
Evaluating FastRawViewer during trial period. I tried to create a custom keyboard command (CMD-S) to move selected image to _Selected subfolder. However, pressing this key combination has no effect. I tried several different key combinations but it does not seem to work.
Am I doing something wrong here or is this a bug? Screenshot attached. I also could not find a way to search the forums...