I am still struggling with a similar problem.
Whenever I create a map inside the "Add-on" category, I can easily tick it in "Main Menu" -> "Mods" -> "Add-ons" and load it inside the GM mode, but when I create the same map as an "Adventure", I can still see it in "Main Menu" -> "Mods" -> "Adventures", but there is no tickbox to use and I can import nothing in GM mode. What am I missing? Do I have to define additional stuff for whole adventures?
Also what is the ultimate difference in creating maps in either mode when I want to use them in Game Master later?