Martin and Developers,
An even closer look at the Python code (as far as I understand it) makes me think that the problem is with ".../pycoast/cw_base.py" in the function "def _get_lon_lat_bounding_box(area_extent, x-size, y_size, prj)".
It seems to me that this function sometimes fails with omerc_bb. One other hint might be that in the case of failure the first meridian (western border) is always 0°. No coasts, borders, rivers that have bounding boxes
with all negative longitude are then drawn (Ireland, rivers and borders in England and Scotland, Orkney Islands, Iceland, Greenland, ...). That's at least what I see in a dozen examples NOAA-20, Suomi-NPP, FY-3D here.
Best regards
Ernst