It was confirmed by many independent sources, including Cointelegraph, and the largest telegram cryptocurrency channel "WhaleClub" that people get their Bittrex accounts disabled for no reason.
Links:
https://twitter.com/btcWhaleclub/status/919261516490248193
- btcWhaleclub
Thousands of people around the world reported their accounts being frozen by Bittrex.
So far, Bittrex haven't answered support tickets. Also, it has been noticed that customers get banned from Bittrex slack channel, which is highly unusual.
Reddit thread: https://www.reddit.com/r/CryptoCurrency/comments/76vntg/accounts_being_disabled_on_bittrex/
People report of being disabled even in United States and Australia
Remember, never keep 100% of your funds on exchanges!