If it reaches the sell trigger and it doesn't sell, that means the indicator you are using is not giving a Sell signal. This can be 'normal' or it can mean a problem with the indicator.

Then, if the market goes down fast, it might already be out of the sell trigger before the indicator gives a Sell signal, so then it wouldn't sell. It's not cool but it's not a problem of the Bot, sometimes indicators don't respond fast enough to certain market movements, they're not perfect.

Personally it has been working well for me, especially after last update. And next update looks even better with the solutions Stephan is working on for out of scope, which is one of the remaining issues right now.