There’s a one-star review of Kidnapped on Amazon, headlined “Meh…”, with the full review being:
“Hard to follow. I don’t like classics.”
Cogent.
In terms of trying to figure out why you got rejected, I think the best you can say is “Forget it Jake. It’s algorithms”.
The whole thing is probably some giant machine learning black box that takes you entire posting and purchase history into account, such that it comes up with something that flags say 70% of the fraudulent reviews and only accidentally calls a good review fraudulent 1% of the time (lucky you), but no human can go in and say exactly why one person or another did or didn’t get flagged.
A possibility off the top of my head could be that you happened to post reviews for products that other dubious reviewers posted reviews for, and so you got flagged for association. The first email you got was undoubtedly pretty much automatically before they had a chance to look at your account, while the second one was posted after actually took that time. Best case scenario your example can be used as an input in the black box to make the algorithm better.
Have you received any emails offering free stuff in return for a amazon review? They may have not directly mentioned it. If you responded, Amazon will ixnay you, even if you didn’t actually post a review.
Maybe. But if someone flags your review, Amazons bots just react. You have to clear it later.
I had a review rejected for a keyboard that listed for $5 but had an $80(!) shipping fee. I mentioned in the review that I could not talk about the actual product as I stopped the purchasing process when I noticed the fee.
I’m going with this. About a year or two ago, I noticed that several of my reviews on Amazon had been deleted, some of them after being up for years with no issues. Like the OP, I couldn’t for the life of me figure out what the problem was. I had put time and thought into those reviews; I relied on others’ reviews and genuinely wanted to help. (Heck, many of those reviews they deleted had been voted “helpful!”) It left a sour taste in my mouth, and I’m less likely to make the effort again.
Is it possible that the products you reviewed were discontinued or changed substantially, so that your reviews might no longer apply?
It’s possible that was the case for some of them, but the few products I clicked through to were the same.
I’ve always said that Amazon customer service in my experience has been consistently excellent, involving things like returns, shipping charges that I didn’t think should have been applied, or help with a failed Kindle software update. No problem with any of these.
It’s not surprising that some algorithm somewhere fucked up and banned your reviews, but it IS surprising that some human in that gigantic company actually resolved the issue. Good on you for being persistent and kudos to Amazon.
Anyone else’s back itchy all of a sudden?
mmm
I have posted quite a few reviews and only once had one rejected. It was very negative - along the lines of “This product is poorly made and not worth the money. I returned it immediately.”
I was a bit miffed at the time, but couldn’t be bothered to worry about it.
That’s why I always have a small pry bar handy.
This prompted me to take a look at my Amazon reviews. I don’t think any are missing, but I did notice that two had been greyed out by a “sensitivity filter.” One review was for an old app called Sketchbook Pro (developed by the same company that makes AutoCAD), and the other was for llama-themed wrapping paper. 
I suspect the word “returned” triggered the bot. I also suspect word triggers for why the OP got flagged, and that a real human didn’t get involved until the reversal.
Well they’re not gonna send an email that says “after a cursory review by an automated system designed to minimize payroll expenses.” 
Realistically, it’s better for Amazon to cast a very wide net even if it means blanking a bunch of genuine reviews. I can’t imagine how many fake ones are submitted each day from bots and farms, but I’m sure it’s quite comfortably in the millions.
It IS a most excellent back scratcher. They have a less aggressive (and cheaper) one too. As I said, they are pricey, but worth it.
The guidelines basically say not to compare the price to the price you’d pay at a local store, because not everyone’s local stores will be the same, and they want reviews to be relevant to everyone. And I wrote a review for an Amazon product last year that mentioned the price, and it went through no problem.
Certainly the algos can tell the difference between an bot account and one that has been buying stuff and reviewing regularly for the better part of twenty years.
It looks like @Chronos found the real reason.
I concur.
One of my favorite things is that when a product is defective, often Amazon will take my word for it, and not demand I return it.
I did? Did you mix me up with another poster?
Nope.