Thanks for checking out the app! The Xenos spawn regardless of selection of the locations. They just don’t show up in the list below unless you have the location selected. This is to keep the spawning secret until the Commandos encounter the Xenos.
I have a newer version that allows you to turn on what I’m calling Tracking Mode and the number of Xenos spawned are displayed in the locations. I also need to change the wording in the pop-up saying the Xenos spawned, but just not in the occupied locations… I’ll have to look at the instructions also to see if I can improve that.