Waves Tune LT glitches when recording to AUX track

I have given up on Melodyne for now due to it being unstable and have been using Waves Tune LT instead.
This seems to work fine on the track I am pitch correcting.
 
However, when I record its output to an Aux track the recorded track is full of clicks and glitches.
I use this technique a lot (to reduce CPU load) with other plugins and have never had this issue.
 
Does anyone know of a fix?
 
Thanks