Same thing happened to me this week. I noticed one day all my reviews were gone!
I contacted Amazon via chat and they assured me it would be escalated to another team and fixed. I have never violated Amazon's review policies and always try to write professional reviews with lots of pictures and helpful info. I also do not receive anything for free and it's all purchased with my actual Amazon credit card, so they could easily verify every single purchase I've made. I dont review books, so not related to or friends with any authors.
Update: This morning I get a canned response saying I "violated their review policy" and that all my reviews were deleted and I can never post reviews again. Also, they say they cannot discuss it further and will not respond to replies. Seriously? Maybe because there is no actual violation and you have no legitimate reason you can use to explain your actions?
All that came AFTER having a very positive chat session with Amazon Help on how they were going to fix my account, had copies of all my reviews saved, etc. My take on it all... maybe it's not Amazon deleting them at all. Maybe they've been hacked and they really can't figure out why it's happening.
So now I have to wonder if my account is compromised. Why would they delete legitimate reviews when they allow "Vine Voices" and affiliate clicks? It sounds like they are deleting reviews from many people who have legitimately purchased and reviewed 100's - 1000's of products, yet Amazon doesn't really even care about losing these loyal customers. I write reviews as a way of giving back and to try and help other buyers make informed decisions about purchases, because let's face it, not everyone has a huge disposable income.
I know I personally will sometimes read every single review before making a big ticket purchase, because I'm currently on disability. Sorry Amazon, but something smells fishy here and it ain't the seaweed wraps you sell.
Product or Service Mentioned: Amazon Review Listing.