plt.savefig saves empty png image

[anbai106]

Hi,

I used your example code to save the image:
ax = manhattanplot(data=df, xticklabel_kws={"rotation": "vertical"}, sign_marker_p=None, genomewideline=None, suggestiveline=5e-8)

plt.savefig(os.path.join(output_dir, 'manhattan_qmplot.png'))

but the saved image is empty