From what I understand, in one case, they had physically disconnected the sandbox from internet and asked it to do something and it had used connections through (import routines) that they had allowed, to pseudo escape the sandbox. Yes it wasn't obviously trying escape the sandbox but it escaped it because it doesn't understand the boundaries and neither do most humans other than the ones that provided the instructions that it had used. So it wasn't a rogue attempt but the fact that boundaries may be not be that easy to set despite what people think.