I'd noticed this whole issue a while ago. The thing is that you can only tell a unit in RTW to move a certain distance. In RTW agents had about a quarter the movement of agents in EB, this meant that the max range would give you several turns of movement. Since the range of agents in EB is so huge, the max range will sometimes not even fit into their single turn movement bubble. And, as said, this max range is effected by the complexity of the map, reducing the range even more.

As a side note, if you are using the movement speed up option then leaving movement beyond what a agent/character/army can move in one turn will cause lag on the strat map.