Bizarre Flex Pitch Issue

I'm currently using Logic Pro X 10.1.1 to record, edit, and mix multiple vocal lines. I've been working with Logic's built in Flex Pitch for a while and haven't run into anything like this before so I was hoping someone could help on the forum here.

I did the vocal editing itself yesterday and it sounded fantastic. The vocalist in question is a bass and I was able to get some great tones. But I came into the studio this morning and listened to it and it sounds like a hamster is singing the vocal line. The pitch itself is not actually higher and it registers as the same octave as before, but the tone is very bright, nasal, and almost cartoonish. What's puzzling to me is that nothing has changed from yesterday to today. Pitch edits, EQ, compression, reverb, bus sends, and levels are all exactly the same as I left them yesterday, but the tone is still very much different and quite unpleasant, which makes it totally unusable in any kind of release.

Please let me know if anyone has heard of or encountered such an issue when using Flex Pitch. I can post before/after samples if need be.

Thanks so much.