Basically play in a combat situation- you'll see it happen. But in my most recent event (with picture):
We've got a heroically wounded, brave squad leader (that would be me) in need of first aid and unit 3- a medic- is standing a house away (in the picture titled MedicTour he is the NPC with the highlighted hex at the far end of the block). He is free from direct fire, is behind cover as well as concealment and has no targets to shoot at.
He is given an order to heal his noble leader. Although all he has to do is walk past a body and another teammate OR walk along unobstructed ground behind them (towards the canal) the medic decides to walk away from the squad and around an entire city block. The screenshot here is taken when he's already run a block away from me, right before he's turned the corner. He is killed.