Why was my order executed/not executed, although the price on the chart reached or didn't reach the order level?

WH SelfInvest charts are based on Mid-price. Thus, reaching or not reaching the order level by the chart does not mean that the order should or should not have been executed, since execution takes place strictly according to Ask/Bid, which are always above/below Mid. Check the current Ask/Bid in the order ticket or in the Buy/Sell buttons on the chart to see the data that comes from the broker and on which the orders are executed.