2 issues which you have to be aware of when you are using BT
1. cancelling an order when it is filled at IB but before BT receives the cancel message. BT won’t know that the order is filled because it will reset once you press cancel.
2. partial fills – there is a possibility that BT may not be able to manage the filled portion if the remainder are filled after some movement as BT waits for a complete fill before switching to trade management mode.
It’s a good habit to double check your TWS while trading with BT to detect anything unexpected.