i am trying to plot maps with ggplot2 and have the issue of disappearing grid lines when zooming in.

I want to use orthographic projection, looking down at the North Pole but not show the full upper half of the sphere.

Plotting the full polar view works, however limiting the window to the desired area makes gridlines disappear. I believe that the issue has to do with xlim in coord_map, but I can not zoom using e.g. coord_cartesian to not use coord_maps xlim.

In the example map_full shows the full polar view with all gridlines and map_zoom shows the desired window, but with the disappearing gridlines (in the top left corner).

Is there any way to adjust the plot window after coord_map with interfering with the existing coordinate system?

Thanks you!

require("ggplot2")
worldmap <- map_data("world")

map_zoom <- ggplot()+
  geom_polygon(data=worldmap,aes(long,lat,group=group),fill="darkgrey")+
  coord_map("orthographic",orientation = c(90, 0, 0),ylim=c(0,90),xlim=c(-50,120))+
  scale_x_continuous(breaks=c(-6:6) * 30)+
  scale_y_continuous(breaks=c(-6:6) * 15)
map_full <- ggplot()+
  geom_polygon(data=worldmap,aes(long,lat,group=group),fill="darkgrey")+
  coord_map("orthographic",orientation = c(90, 0, 0))+
  scale_x_continuous(breaks=c(-6:6) * 30)+
  scale_y_continuous(breaks=c(-6:6) * 15)

map_full
map_zoom