hi huwcole, yes we have try it, we still not very sure what is the problem. because it just throw error right away without any additional information. we suspect plupload unable to get image size of gif image format. if you remove “max_dimension” it going to fix the issues, but it will give your website bigger issues, people can upload image weird size of image, like 1x2000px image. we will still recommend you to use this filter.
i think png can substitute usage of png format. it will also have transparent effect like gif image.