Sorry for bringing up an old thread, but I found this while googling for the same issue and want to state a fix for others, or OP if they're still around. As you heard, this glitch is caused by having Walking Cloud as a companion. It causes Joshua's "NVDLC02JoshuaNarrowsForceGreetTrigger" script to glitch. I can confirm through my own testing it has nothing to do with mods or load orders, as I've had it occur on multiple playthroughs, and without any mods that make changes to the Honest Hearts esm. As far as I know the only way to fix it is to reload a save and reject Walking Cloud's offer, in which case the conversation will trigger as normal. Then you can go back and recruit Walking Cloud.