Not wanting to stir the pot after it has cooled however I offer the following.
Are these cracks developing as a result of excessive spanwise bending caused by leading and lagging of the blades? It has been proven that leading and lagging are present but highly restrained by the cone hinges. The cone hinges show evidence of this in their elliptical wear pattern. Two things are present. The cone hinges react the leading and lagging and wear accordingly. The reacted loads are reflected in the blades flexing along the spanwise axis. Once the cone hinges wear the blades have very limited movement relative to their fixed position. This movement can exacerbate the loads on the blades by the shock of the movement of the blade moving and hitting the restraint of the cone hinge wear level. The greater the wear the greater the shock level.
