Studio One does not support the ability for Auto-Tune® Pro's Graph Mode window to be resized (either by changing the dimensions in the Preferences menu or by clicking and dragging the GUI window).  This issue unfortunately affects the VST3 version on Mac and PC.

However, the AU version is not affected by this issue, so if you must resize Auto-Tune Pro's Graph Mode window, please use the AU version in the Mac version of Studio One instead of the VST3 version.