Arrow keys not working in MainStage 3.2.4

Been using v3.2.4 since it came out and recently have experienced that occasionally all of the arrow keys will cease to advance the patch/set in full screen performance mode. This only happens intermittently and is always fixed by restarting MainStage. In this case, I'm using a Mac Mini i7/3GHz/16GB/256SSD/OS10.11.6. Also running Ivory Grands II v2.1.3.

I'd be curious to know if anyone else has had the same issue and if they've found a cause. I'm suspecting that it's related to the latest OS X update.