You can definitely have compression fractures and not have set. Some years back I cut a beautiful straight Mockernut hickory. I split out 6 staves,took them to bow dimension,cured them on a reflex form,then set out to build the bows. The first 5 staves I heat treated the belly,as I always do. All 5 developed CP's. The 6th stave I passed on the heat treating,and it made a good bow. Who knows what made this wood susceptible to chrysals, when wood taken in the same area never caused a problem. God Bless