Grim woohoo not working

I have a completely full relationship and friendship bar with grim. I want to have a child with him for a legacy challenge I'm wanting to do, however every time I queue up the interaction it either disappears, changes to a different interaction, or they will do the little giddy action as if they are about to and then just stand there doing nothing before going back to random conversation. I have reloaded the game multiple times and it will not work. What do I do here.