Exact same issue here. Wondering if I missed something along the way? Cannot equip or modify the unit either, if that was the intent.

Maybe it's because Horses and visual Armor haven't been made part of the Royal Knight unit yet?  That would be my best guess.

Best regards,
Steven.

Unless you have a metal mine, no armor unless you tack on leathers.  At least you can give them swords (I think they don't require metal but can't remember).  They shouldn't call them knights.  The term knight implies training with heavy armor and a variety of weapons and fighting techniques.  These spuds obviously lack this.  Maybe their mad because they are still landless and can't afford gear yet.  If they sang you could call them, "Motely Crew."  They at least have big hair.

I had the same issue in my game.