well qnnpack is disabled by default on x86 systems per the info here: RuntimeError: Didn't find engine for operation quantized::conv_prepack NoQEngine · Issue #29327 · pytorch/pytorch · GitHub 30
that link also includes a workaround, did you try that? I can see that you posted there as well.
more info here too: The Feature Request of Loading Quantized TorchScript Model on Windows with libtorch · Issue #31684 · pytorch/pytorch · GitHub 5
if you still can’t solve this, could you open a new issue in the forum and include your env information?