Motion 5 System Freeze / Crash

I am using motion 5 to create an animation. I am using only bezier shapes and regular shapes that can be built in motion. No video or stills.

The issue has occurred twice while changing the parameters of an oscilate behaviour, well, once while closing the hud after completing my changes. Other times it will be fine.

I am looking solely at the group that i am oscillating, not the active camera and i am working within a 500 frame play range. When the freeze occurs i have to "hard reset" as the mouse is static. I still have response from the Caps Lock key light, but no key commands work. Cant force quit.

The issue is sporadic.... any ideas?

I am working on a Top Spec Retina MBP 15 with 512SSD and 16GB ram.

Any ideas how i can stop this? cos it is a pain in the proverbial backside!

Regards

G.