I have recently stumbled upon multiple problems:

• The P key cannot export underground maps, which means I need to manually screenshot every single part of the map.
• The underground is very dark, causing some display problems which I try to counter with over 8 stacks of torches already.

However, the greatest problem:

• The underground map resets when disconnecting.

With me not being at home for the rest of the month starting tomorrow, I will do my best in working on the map - but I doubt it will be successful. :/
I guess the next UCP will be a far easier one, also one that is located on the surface. ._.

 

The problem is that the mapwriter underground mode is based on the real light level. :(