Hi @HashedViking, did you update submodules, like running git submodule sync && git submodule update --init --recursive --jobs 0 before running USE_PYTORCH_METAL=ON python setup.py install --cmake to build PyTorch?
I had the same issue and solved it by running the above commands in the main branch(commit 2992d92b5acb1e5c712e5e9fded652f1312a81b1).
Let me know if there is anything else I can help.