Simply put, there are too many bugs breaking the experience, and you just found yet another one of them. Just go back to to 8.1 -> Update to W10 10586 through the Upgrade Advisor -> Once upgraded to 10586, you'll get 14393 -> STOP. Make sure you are not enrolled in the Insider Program in Settings. Also, 14393 is officially supported on Lumia 930/1520. It still has a few minor quirks, but you won't be hitting those very often, if at all.