Bittrex is solid, but last year they de-listed many coins which couldn't prove that they are not a security and recently they moved their non-US legal entity from Malta to Liechtenstein (Obyte Foundation and its bank account is also in Liechtenstein). https://medium.com/bittrex/bittrex-international-update-bittrex-global-launch-2f64fca503fd

With the change of legal entity, they also stopped to service certain country residents https://bittrex.zendesk.com/hc/en-us/articles/360034965072-Important-Information-for-Bittrex-International-Customers
If you are in any of these listed countries, you have until November 18 to withdraw all your cryptocurrencies. So, I would not recommend holding any crypto on any exchange for other than when you need to actually exchange it, no matter how solid they are. Keeping Obyte on centralized exchanges doesn't make any sense either because it is cheap to send and doesn't take more than 15-20 minutes to be fully confirmed.

For those who have trouble accessing Bittrex US or Bittrex Global, there are multiple coin swapping services listed on Obyte website. https://obyte.org/#exchanges