After setting units to auto explore, if I take the units and deviate them to manually search a ruin or something, I can not get them to start auto exploring again. I turn auto explore back on but they don't move. Eventually when clicking on the unit and end turn and auto explore I've gotten them to start to move again, but I'm unsure what actually fixed it. I have only been playing the Windwalkers, but I can not say if the other races have the same problem.