@robomatic - can you provide the motors/esc/battery configuration you are using? A Hex will absolutely be able to fly with 5 motors as long as they can make up the difference for the lost motor. I have personal experience with early DJI Naza-M V2s being able to handle this. I keep one switch position in Poshold and Super Simple mode for just this emergency on my Arducopter Hexas.
As you can see, in the first one the weight is all in the middle, meanwhile in the second, the camera on the front, and the battery is compensanting the camera weight. May be that can be the problem? Or a bad PID setting?
The main question maybe will be in one of the PID is more related with the weight in this case, the P on the yaw?
I would expect the spinning in most cases. They key is being able to land safely after a motor failure, which it appears you were able to do. Review the link from Github from my previous post, in particular Tridge’s thoughts on the the AP’s configuration, and it may give you some idea of what to expect and what may help to mitigate motor failure.