M-Level is for Multi Level Assets this allows you to add assets that span multiple levels.
If you just want to add tiles to the Modular subsection in Pack Creator select Objects under the Palette Tool section click on Objects and you should see a drop down. Select Modular and add your new sections and Map tiles there.
Hello, I have a problem with M-Level when importing several multi-level houses. When I add the first multi-level house to the preset everything is ok, but when I click to add the second, third etc. to the preset, it adds more copies of the first house. Any ideas how to get around this? Thank you 🙂