I have experienced this bug with many (if not all) Arturia plugin from V5:
After initializing a plugin - after some time the GUI will disappear for a short while and this causes playback in Cubase to stop!
Only happens at first playback.
Maybe copy protection related?
Only happens with Arturia synths.
VERY annoying . please look into this Arturia / Steinberg.
Macbook Pro Retina mid 2015 on OS X El Cap 10.11.6
Video link (happens at the end) http://tonekontrol.dk/temp/IMG_2642.MOV