Ok, last time I went on DI was long ago, so correct me if I'm wrong, but I remember a problem...
When you want to invite someone in one of your Age, you can use the KI invite, but you can't use the "share book" icon on a book, nor on a Bahro Stone.
What's is wrong, exactly ? On my offline version I brought back this function, it seems to work, but I can't test it in multiplayer mode and I prefer not to hack DI python files...