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I still have a working Basic account (US resident), but I've lowered my exposure. I don't know what to believe. Bittrex says only a tiny portion of customers are affected. None of the traders I follow seem affected. But there's a lot of activity on these threads.

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The first huge problem is that Basic verification seems to only work for US residents. People from the rest of the world are forced to make an Enhanced verification by sending selfies and scanned IDs to Bittrex (which is something not everyone is willing to do) and even then it may not work.
The second huge problem is that Bittrex silently downgraded a lot of accounts basically freezing the funds of many people thus forcing them to do an Enhanced verification because Basic one doesn't work. A simple email a few days before doing these account changes would be more than enough, because it would give users enough time to withdraw their money if they were not ok with the changes... I hope I'm not right, but this can soon turn into both money and personal data theft, so be careful.