Moment of Reverence Boss fight buggy

For some reason all or Originator boss fights is buggy and boss skills is not loaded in time or isn't even loaded. Also boss arena textures is not loaded or loads after some time. I am trying to understand what is happening but I suppose the way how these boss arenas and boss skills is not optimized. I started to notice this when Originator bosses was introduced, but now because of this problem I cant progress if I don't see anything what hits me.