Gridlines are not being plotted correctly with several projections, including Mollweide and Orthographic. The problem is that the gridlines do not continue all the way to pole, but simply stop at something like 85 degrees.

Here is some simple code to demonstrate the problem

fig = plt.figure()
ax = fig.add_subplot(111, projection=ccrs.Orthographic()
ax.set_title('Orthographic')