As I mentioned in another forum; I had the exact same problem and solved it by uninstalling the 'Live Lock Screen BETA'. Even when the program was reportedly not running it caused my battery life to plummet and my phone to overheat.
Good advice, I had the same issue. As also mentioned in other forums after unistalling the app you have to go under settings and turn kids corner back on to get rid of the problem completely (don't ask me why but it works probably overrides permissions or deactivates some of the app code left on the phone).
Yet neither of those work for some users. They are masking some symptom. I'm convinced it is tied to the new API for "back button" and some apps are still having background processes running if not closed all the way by accident from the users's app closing method. It also seems to go hand in hand with indexed files in storage (media, documents, etc.) from my experience.
I never had Live Lock Screen Beta and I had the "resuming" or "loading" screens. Activating and deactivating Kid's corner did not solve it.
Removing Cortana from the start screen worked, but also at the same time I was
watching to be sure I always backed out of apps to close them. Then long press back to get to card view and tapping "X" button on any persistent apps (never swiping the app off screen). I haven't had an issue for quite some time and I cautiously added Cortana back to my start screen... Still no repeat of the problem.
Masking the symptoms is not a cure, nor is finding a root cause to avoid. But knowing how to avoid the problem sounds the better of the two (mask or avoid). Those with success by removing Live Lockscreen or enable/disable Kid's Corner or removing Cortana from Start... You may see your symptoms return. If you do, I would suspect the wrong app closed by the wrong method and bet dollars to donuts that app reads media indexing.
It won't be over until Microsoft puts out a bug patch.