Did you move the note substantially? The farther you move the pitch, the more robotic and unrealistic the vocal track will sound.
If you don't believe this is the issue, I would look into the formant controls. Sounds funny, but you might unintentionally be telling the software to turn you into a woman
compare the sample rate of your original recording vs one with melodyne applied and armed. If they don't match and you upload a file with a different sample rate onto your project, you can get robotic glitchy sounds as well