Shortbreads falling apart

Every christmas, I make cranberry-pistachio shortbread cookies. It’s the type of recipe that you roll into logs, chill then slice. My problem comes that when i slice them, they sometimes fall apart and im trying to squish the pieces back together. Any hints? They are also a little hard to shape into logs, a little stiff. What can i do to fix this? Less flour? More butter?

https://www.justsotasty.com/cranberry-pistachio-shortbread/#wprm-recipe-container-13908