I have been answering 2 support tickets for more than two months.
They allow the purchase in btc of COX and do not allow the sale when they can not be moved to another exchange. Yobit is stealing user's coin in that way and it's not the only currency they use to cheat. BEWARE THIS IS A SCAM
Yobit support problem is nothing new. A lot of people lost their money in trying to withdraw them from yobit - you aren't the first, and you won't be the last.