The USDT accepted at ACE Exchange is based on the Omni Layer.
Therefore it's not the same technical standards used under the Ethereum technology, so USDT Omni layer and USDT Ethereum are unable to transfer to each other.
Please do pay attention if you are going to perform a transaction.
If you need further information, please contact us through the following information:
【ACE customer service center】
Help Center: https://helpcenter.ace.io/hc/en-us
Business hours: Monday to Friday 10:00am-06:00pm, Lunch Hour 12:30-13:30 (GMT+8)