According to this article whilst autopilots and pilots individually seldom make mistakes, errors sometimes occur because of "inefficient collaboration" between them and this has been known to have caused accidents.
To avoid this new software is being developed that gives the autopilot more calculation work to do. The result is that the human pilot is presented with explicit statements of the current situation, action to be taken and objectives. This gives them a better understanding of what is going on and hence what their part is in it all. Also, it reduces the workload on the pilot, leaving them to spend more time monitoring situations.
It is interesting to read about how errors occur between automated systems and humans, and this could be entirely relevant in other industries such as process control, where I know optimisers can cause confusion. Whether this new software is the solution, I am not so sure. It sounds like the pilot's role is being further eroded, becoming more passive and boring, which may not help their alertness and may even lead to a degradation in skill over time.