Thanks for sending the files! I think the first issue on startup is a bug that I need to fix related to scripting. The other issue with loading the dungeon map appears to be related to the quick script that you have on the Dungeon Entrance tile.
Here is the current quick script:
load_map("map_name", coord[-6, 3, 1], SOUTH)
You'll want to modify this so "map_name" is the name of the map that you want to load, in this case "Dungeon01":
load_map("Dungeon01", coord[-6, 3, 1], SOUTH)
You'll need to do a similar thing for the stairs leading back up to the "example" map. I think there may also be an issue with the navigation paths on the stairs in the dungeon map. I'd recommend deleting and re-adding the stairs and then using this quick script:
load_map("example", coord[3, 2, 0], WEST)
Hopefully that helps! I'll get a fix for the startup issue released.