Pitch II does not work properly!

[Cartoonguy]

I have used the Pitch Shift plug in that comes with Pro Tools for years to pitch voices up maybe one semitone. It always sounded great, but now I have Pro Tools 11 and when I use Pitch Shift II to pitch, say, one semitone, it comes out with very noticeable distortions and kind of bubbly sounds here and there, like it's underwater. Not really useable for anything serious.

This surprised me because I had been using this feature on older versions for broadcast work. Never a problem. So I got an old copy of Pro Tools 8 and tried pitching the same sample up one semitone. Lo and behold, it sounded perfect. Same thing in PT 11 and it sounds terrible. Totally unusable due to the noticeable distortions, or whatever it can be called.

Why is Pitch Shift II in PT11 proving to do such a terrible job compared to the old Pitch Shift in PT8? I am using a brand new iMac, by the way.