SCAMMERS!
They put BTG wallet in maintenance 10 days ago, making tons of deposits inaccessible. They are lying that they need feedback from developers. (Meantime, other exchanges fixed BTG issues in days.)
And Bittrex's support is unable to help, actually they have no willingness to solve the issue.
Sorry, guys, but my issue has been solved in two weeks with support and transaction error. And support solved this problem not me. Yes, it was not so quick but I understand that so big exchange has many issues as you say
They are forcibly closing my tickets without any meaningful work, which is a very questionable behaviour.