Your issue is as Wayne says, standing too far from the target. I have done the same thing with my spruce shafts and it is very frustrating. Called Wayne so he could talk me off the ledge lol. The nock end will snap around quickly and snap that shaft like nothing. The woods have lots of strength through them pile to nock, but laterally thats when they break. I have found that with all the softwoods I have shot. Clip a hard object, like a live tree, suddenly changes the direction and they lift a splinter, or explode. Spruce, poc, hemlock or fir they all seem to perform well, until that sudden change of direction. And I beat the tar out of my arrows:)
I have found western hemlock to be a solid arrow shaft. Nothing to complain about thats for sure. I need to do some bare shafting soon, maybe we can work together on it. I have a foam block target I can bring.