I also have experienced this. Even after trial time (not yet purchased).
This is an useful comment. Since after the trial, all buildings disappears, at least we know it's not something related to the 3d scenery, or LOD optimizations. I guess it might be texture loading, probably for the background. A solution might be lowering the global maximum texture size slider one notch, since it will revert to using 512x512 textures at maximum, instead of 1024x1024, basically as it was in Zurich 1.0.