Al tho the grain don't look that good I think it was to dry or dry rot,the way it broke straight across.
I have run into that a lot and now if I have any question on a stave I take a small sliver off of it and do a bend test ,if it breaks like pop corn across the back I make fire wood out of it. Had some
hickory and ash act the same way.I figured it was the place I had seasoned it,not out in the weather
but under an open shed and most white wood will dry rot very quick.Sorry about your luck but it happens.
Pappy