SharpenAI Standalone Image zoom

I have just received my upgrade of Sharpen AI and have been trying it out.
It would seem that loading an image into the standalone version loads it to 100% magnification. Instructions suggest I can zoom out by pressing ctrl± . I seem to be able to zoom in, but zoom out does nothing whether I am at 100% or greater. I should like to be able to zoom out after applying the tool to see how the picture appears at lower mags, but there is no way to do this. What am I doing incorrectly or is it intended to work like this?

Zoom is available at 100%, 200% or 400% from the Zoom drop-down only at this time.