Is this happening all the time or just this once? It could be that the spot the autofocus was pulled wasn't contrasty enough and it just provided a bad solution. It is really important that it isn't moving at all when the autofocus is pulled because that messes up the successive contrast calculation. Try to pay to attention to that if you can.
It won't do the focus pull when you tap unless the Aircraft is dead stopped. That might be the issue too.
Otherwise, sync the mission to your MME account so we can take a look at what is happening when.



