cartopy自定义形状边界和立体投影无法添加网格线

Question

我正在绘制以南大洋太平洋地区（160E~180~60W，-60S~-90S）为重点的自定义形状边界图。添加网格线时，区域（180~60W）缺少网格线

我尝试了很多解决方案（主要针对矩形投影），但都失败了

import matplotlib.pyplot as plt
import matplotlib.path as mpath
import cartopy
import cartopy.crs as ccrs
import numpy as np
proj = ccrs.Stereographic(central_longitude=228, central_latitude=-70)
fig = plt.figure(figsize=(10,10))
ax = plt.axes([0,0,1,1],projection=proj)
latmin = -90
latmax = -60
lonmin = 150
lonmax = 305
lats = np.linspace(latmax, latmin, latmax - latmin + 1)
lons = np.linspace(lonmin, lonmax, lonmax - lonmin + 1)
vertices = [(lon, latmin) for lon in range(lonmin, lonmax + 1, 1)] + \
    [(lon, latmax) for lon in range(lonmax, lonmin - 1, -1)]
boundary = mpath.Path(vertices)
ax.set_boundary(boundary, transform=ccrs.PlateCarree())
ax.set_extent([170, 320, -90, -60], ccrs.PlateCarree())
ax.add_feature(cartopy.feature.LAND, zorder=1, edgecolor='k')
ax.gridlines(draw_labels=True)
plt.show()