This has happened two times already. I reported it immediately once it occurred. The staff said they are checking. None called back. Also someone working in IB here asked me to submit my account details. I did. Still no response. How could I place my trust and trade if even the most basic function - stop loss - has bugs? I have reported various bugs about orders for the last few months. None of them have been fixed so far. Back to the stop loss problem, here's what happened. I created a buy order of an HK stock with a stop limit attached. The buy order was executed. The price went up and I changed the stop price several time. Finally the stop price was adjusted to .69 (limit price .64). In other words once the price reached .69, a sell order of .64 would be sent to the market. The price dropped to .69. At that time the price was still struggling at between .68 and .69. But my stop loss was just stuck doing nothing. I had to submit a market sell order instead to exit manually. At that time I was exited at a much worse price. Testing in PaperTrader. The stop-loss works. It just doesn't work when it comes to reality.
Maybe, you want to post fxing this issue as an improvement request on IB polls (suggestions) page. Then clients can vote for it and the number of people will add weight to the severity of the problem...
Hong Kong. The OP has posted a different thread on this issue earlier: IB Stop loss not working in Hong Kong Stock Market
I don't know about HKFE but on GLOBEX, Stop Limit orders are native but IB simulates them and holds the order anyway. I still haven't figured out how to make a native Stop Limit order on GLOBEX if anyone figures it out let me know. That may be the source of this problem.
I have no idea. I've only recently become aware that they are doing this and not giving an option (that I know of) to route Stp Lmt orders to the exchange. I just simply never thought about it because my stops have always been filled at fair prices so there was no problem that I could see with this. IB does offer some valuable services by offering simulation when the exchange doesn't support order types natively (Market and Market if Touched as an example) but I am equally perplexed as to why they would simulate orders that are supported by the exchange. Maybe a rep from IB can clarify. The conspiracy theorists will have some answers I am sure . I have not noticed any price disadvantage to this but now seeing this problem the OP is having makes me want to have the order at the exchange if at all possible to prevent any case of it not getting executed (internal problem at IB servers for instance).