I very like this plugins since I installed last week. But I found it not working for picture in PNG format. Can it only be used in JPG image format? I think it might be a bug. I would appreciate your help with this. Thank you!
And Some Information
WordPress version: 4.9.8
Image Watermark version: 1.6.4
Watermark format: png with transparent canvas
Image format: jpg is working and png only have watermark with white background（It seems that the original image was completely covered.）