Actually
reducing the playback i/o buffers helped solve the "issues" I was/am experiencing with a project ported over from X1.
Interesting that I am using a UFX (USB) interface.
I've had 1 or 2 audio engine dropouts since, but I was at a point where playback stopped every time in exactly the same spot.
No audio snap or melodyne/v-vocal instances "lurking" about.
Tom