Mouse wheel does not zoom the image in crop dialogs

In every image crop dialog (for example, the one that appears after selecting a new image in User Settings → Profile), the instructions say you can zoom by scrolling the mouse wheel or pinching with two fingers. However, scrolling the mouse wheel has no effect on the image in any of these dialogs. The only way to zoom is the “Zoom” slider below the preview.

Open any feature that uses the crop dialog (e.g. User Settings → Profile → change avatar) Select an image so the crop dialog appears Hover the cursor over the image / crop area Scroll the mouse wheel up and down Repeat with other crop dialogs; the behavior is the same