Post any defects you find in the released or beta versions of the ImageMagick software here. Include the ImageMagick version, OS, and any command-line required to reproduce the problem. Got a patch for a bug? Post it here.
I found some images on our website, where the scaled version of a non-transparent image was completely transparent without any other content. Is this a possible bug or did I completely misunderstand something about it?
Your sample image is too large (52MB) for me to download, sorry.
GIF has binary transparency: each pixel is either opaque or transparent. If your resized TIFF image has graduated transparency, I suggest you either flatten it against a background colour, or threshold the alpha channel at 50%.