Did the bullet directly strike the vertebrae bone or the scapula? Do you have a neat little entry on the other side? Heavy bone shots are interesting, in terms of how the bullet performs.
It's interesting to compare the 6.5mm 143gr ELD-X and the .243 100gr ProHunter. Me and the wife will shoot close range deer (sub 150m or so) in the neck with the ProHunter, depending on the position of the animal usually the C1/C2 vertebrae below the rear of the skull. The ProHunter at 2800fps will obliterate the vertebrae and vaporize the bullet, all you'll find are little bits of copper jacket and a grey lead coating on the neck meat around the wound.
But it never exits. All you'll find is a the neat 6mm wide entry. This spiker is a good example, shot at almost bang on 100m, you'll not know its been shot until you pick up the head and realise the spine is pretty much completely disconnected. Entry on left photo, other side on right.
With the 6.5mm ELD-X, which I only really use for medium range shooting, in general a side on chest shot between say 250m and 600m will punch through, but the exit hole will be half the size of the one in Mungo's photo above. One of my favourite shots is from steeply above, as you have clear access to the CNS. This one was shot at -27° at 325m or thereabouts, in through the T1/T2 verterbrae, down through the front of the chest cavity and into the rear of the brisket. No exit. Neat 1.5" diameter hole through the spine, below the back muscle, which was largely undamaged. Remains of the bullet shown.
The 143gr ELD-X for me is a longer range bullet, I have shot short range game with it (only goats I think) but I wouldn't choose to use it as a stalking bullet where I'm anticipating animals close in, so your comment about 150m+ makes sense. I'm certainly not surprised to see how its punched a hole through the little roe at that range after impacting hard bone.
But.. there's always a but... whilst I get the focus on meat recovery and fussy game dealers and so on, flattened instantly dead deer are a nice-to-have especially when you're in or adjacent to the woods, and in that sense the ELD-X excels. It delivers one helluva thump to a roe, fallow or red deer and assuming you've shot it in the front half of the chest, they certainly don't go far if anywhere at all. It's quite forgiving of shot placement in that sense.
Bottom line is that I prefer a lighter frangible hunting bullet at close ranges, say sub-200m, one that I can bank on impacting where I want it, stay in the animal and not create gaping great big wounds. That's what the ProHunter excels in.