20200706:
If you are using Cubase 10.5, considering upgrading to Auto Tune Pro 9.1.0 on Windows 10.
If you are using Cubase 10, consider upgrading to Auto Tunes 8.1.1 to work on Windows 10.
Otherwise, read on…
The best method is to load your Soundtoys > Microshift plugin first, before loading Autotune 8.
Otherwise, start Cubase 10 in Windows 8 Compatibility mode.
See thread:
https://www.steinberg.net/forums/viewtopic.php?f=286&t=147324&start=25