Avatar animation's go wacko from PC to Mac

I'm building a demo space using a PC. I have avatars dancing using avatars and animations from Mixamo. When I transfer the files over to my iMac using Dropbox, the avatars are no longer in position. I reposition them but if I choose anything other than "default" in the Animation Wrap Mode (for the animations)the avatars transport to a different location during play and the animations go wacko (yes wacko) with the avatar jumping all over the place. Is there something I'm doing incorrectly and corrupting the file or something? Has anyone else had this issue? Thanks