The server uses the maps to determine Line of Sight. By default, the server is configured to assume no NPCs have LOS if no maps exist, so they won't aggro or assist anything because they can't "see" them. You also would have found that spells wouldn't have worked, either.
This behavior can be changed in the code, but it's for the best. If everything had LOS by default without maps, then dungeons would be a mess, NPCs running through walls and floors and the like.
Of course, with the maps everything works properly so there is no need to worry. I'm glad you got it working
