I didn't put this in the bugs report because I suspect it is not one.
My main town of Bindi (20|97 Littlefield) is in the northern tropics and her 2nd town is actually situated on the desert. The main town has tropical landscape but the 2nd town has the 'normal' or grasslands style landscape.
It is either because the town in located in the desert and no landscape has yet been assigned to that area or it is bug.