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.
Your image converts to MPC format perfectly fine under IM 6.9.1.1 Q16 Mac OSX. Version 6.7.7.10 is over 130 versions old. I doubt the IM developers will patch such an old version. You would be advised to upgrade. But I will defer to the IM developers.