Hello,
the zoom needs for the uploaded image to be bigger than the presented image. In your case, this image is 783px wide and presented as a percentage of the browser width (9/12 or the content container), which for my screen size means a 868px width. I assume your chrome dev tools open on the right side of the screen, which it shrinks the website’s width along with the image’s width (something below 783px), therefore the zoom starts working.
The solution is simple: you need to upload a bigger image, that’s all. By bigger I mean wider and taller, the resolution doesn’t count here.
Another solution is to upgrade to the Pro version and use the Zoom Level option which lets you zoom in also when the image is too small, but it’s still recommended that you upload a bigger image, because the zoom will be a bit blurry.
