torch 2.3.1+cuda12.1 with flux lora train, but got the train error when use single GPU, pls help

## Error
When I use 2 GPU to train flux lora, everything is fine, successful training~, but when I use one GPU or start with 2GPU, but use one, it start to have the error bellow,
I tried :
export NCCL_DEBUG=INFO
export CUDA_DEVICE_ORDER="PCI_BUS_ID"
export NCCL_IB_DISABLE=1
### Environment :
lion-pytorch 0.1.2
open-clip-torch 2.20.0
pytorch-lightning 1.9.0
torch 2.3.1+cu121
torchaudio 2.3.1+cu121
torchmetrics 1.4.1
torchvision 0.18.1+cu121
nvidia-nccl-cu12 2.20.5
centos 8 system
please help!

No source files, tests, entry points, or textual traceback are identified; the error details are only in attached images. Start by extracting the traceback and reproducing the Flux LoRA training run with one GPU, then compare it with the successful two-GPU run; done means single-GPU training completes successfully.

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