I haven't successfully traded at IDEX. I used to wanna transfer the coins to IDEX to sell them. However, the transfer was not successful and i gave up eventually.
What does the error says? most of the traders here can't say anything bad about IDEX and most of it are all positive. And the incident that happened to what OP wants to address is different from others experience. There's someone claiming that he has lost his ETH and a guy hacked the wallets sent to another wallet. Just be careful whenever you are trading to any exchange, everything on internet is vulnerable.