When there are two of my units adjacent to each other, you can perform a unit swap between their two hex tiles. You do this by dragging the cursor of one unit over the other. The cursor turns white, let go of the mouse button and the units swap tiles.
I find that sometimes I select unit A and find that trying to swap with unit B does not work. However, switching to using unit B to initiate the swap does work. Why is this?
Best Answer
Normally I find this when the target (the one I don't have selected) is fortified. When you select a fortified unit it is unfortified (at least in appearance/temporarily), so then you can swap it with the original unit.