That is with full algo trading, it can happen all the time of a sudden. That is why any full automation needs to be babysitted. With any retail software and retail coding you cannot get out of this I am pretty sure. That is why I only trade manually. I have anytime full control of any orders.
There really can be a lot of issues why this can happen. I cannot write a book here nor I am able to list all kind of possible errors when it comes to automation.
Sorry, but you cannot leave the trading desk when trading. That is sad but true.
Babysitting isn't always required but it takes a very long time to work out all the possible issues. It takes years because most of the problems are not obvious at first. But you're right that some commercial piece of software is unlikely to handle all your nuances.