The following reasons could be preventing the pending order from being executed:
1. The available free margin in the account, is insufficient to open a new position.
2. The price of the pending order is incorrect and does not meet the execution standards of the pending order.
3. When major financial events are released, the market may fluctuate, and the actual price of the order may be different from the pending order price.
Please note that the failure of pending orders to be executed is not limited to the above reasons and must be determined based on specific circumstances at the time.