I've had this happen as well. Even though it doesn't show up when you hit the home button it will say *app* recording at the top of the screen when you exit. If you double tap the red bar at the top of the screen the app will show up. You can then double tap home and it will show the app and you can close it normally by swiping upward.
OS 10.10 iMac (mid 2012) i5, 16gb ram, Scarlett 18i20, Cubase 8.0.5 64bit. CMC-TP, CMC-CH, CMC-QC, CMC-AI, CMC-PD