Same exact issue as what is going on in this thread. We need a good solution for archive pages, as the documentation mentions MB_Relationships_API::get_connected has performance considerations when loading many posts. We need a fix for MB_Relationships_API::each_connected or an alternative, since this was previously working functionality that seems to have been inexplicably removed.
Currently, there is only one way to display relationships on the archive page. However, I don't see an impact on performance. I've also escalated this issue to the development team to fix it. I will let you know when it's done.