When the animation is done rendering in another 12 hours I'll try to figure this out. In the "resample key frames" window there's an option to fill keyframes every X frames, for the selected parameter or all parameters for the object. I'll see if I can reproduce the problem that way. I suppose it could be a memory issue, although I have 16GB on my 2013 MacBook Pro and the Poser file isn't huge (the .pz3 is 29MB and the .pmd is 59MB).