I am working on a close earth-analog. History has progressed into a modern-equivalent age. For purposes of the answers, current earth may be assumed.
That's your basis and in this world there is no way that such a run of zero death would go unnoticed.
For a period of about two weeks; death stops. Everywhere, for all humans.
Accidents that would normally be fatal are no longer so
So every ER department and hospital will notice zero deaths for two weeks ! That alone would cause an instant investigation as to why. At the very least medical people would want to know how to keep making that happen.
I wonder if any major hospital has ever experienced a day with zero deaths.
But that ain't all.
Just a few people monitoring and watching closely will be insurance companies (believe me - they'll notice all the money it's not costing them - that they'll keep !), first responders ("Hey, that guy who was decapitated is still alive !"), the morgue ("That's the hundredth corpse that got up !") and the odd suicide case ("but seriously I used explosives - what do I have to do ?").
assassinations fail due to circumstance
Assassins don't just try and if the first attempt fails for unknown reasons they give up and go home. "Finish the Job" means everything in that business. They're going to notice because eventually they're going to try smashing someone's skull to pulp with a large blunt object and that's not going to fail expect in very, very, very, very ... you get the idea. The thing to remember about murder is that leaving a live witness is absolutely not what you will opt for. Try, try and try again is the order of the day.
The same, incidentally, must be said for the military. Military bosses tend to get very irritated when they send people to wipe out something else and it doesn't happen. Not happening continuously for two weeks ? At some point people are going to start pointing weapons directly at the people who "fail" and when that doesn't work ever, they will think how odd it is.
diseases are halted or are cured entirely
So the patient with dead kidneys, rotten liver and a completely dead brain is going to be cured and you expect no one to notice this happen the many times it will in a hospital ? In ICU life support is turned off and a clinically dead person just stays alive ? You think they won't notice this happen ?
And you think they won't be even more suspicious when death "turns on" again and for no apparent reason the same people spontaneously die ?
Medical people tend to be curious about little things like that.
, and all other methods of death either fail, are of lesser impact or otherwise resolve.
So even if you ignore all the terminal cases and murders that fail despite repeated attempts, there's no way hospitals, the police, administrators, insurance companies and all those myriad of organizations that not only can't avoid death but in some way exist to serve it (the word "undertaker" leaps to mind) won't notice a 100% drop in work.
Think of the hundreds of thousands of YouTube videos on all those mobile phones capturing all the miracle not deaths. No one will notice ?
Yet, none of this is noticed either during this time or after death resumes.
And this is even less likely.
For decades, maybe even centuries, people would be curious about why no deaths occurred for two weeks. Think of all the relatively minor historical mysteries whose resolution can have no bearing on our lives but which some people are still researching. Humans love mysteries and people will certainly notice.
But it's even worse than that.
Not only would they notice it but people would, during that two weeks, start experimenting and trying not death-defying, but certain-death stunts in the "certain belief" they'd survive. This will happen a lot and then, suddenly people will start dying again. Whoops. People, even idiots daft enough to try these things (many YouTubers leap to mind) will spot that the magic no longer works - but not spot it for long.
And then people will really start asking questions.
So your idea is, if I may put it this way, a dead duck. Eventually. :-)