Hi, I'm afraid know nothing about Zbrush but I do remember seeing a post about this over at DAZ a while back, so here it is: https://www.daz3d.com/forums/discussion/363291/importing-models-with-texture-from-zbrush

This may help, I hope it does. Bryce is pretty old and there could be things coming over from Zbrush in the obj that it doesn't understand. If the post doesn't help, try posting an image here showing exactly what's going wrong with the mapping.