🖼️ Fix Black Image / Video Output in ComfyUI When Using SageAttention

1. Install ComfyUI-KJNodes
Open Extensions in ComfyUI.
Search for 
ComfyUI-KJNodes.
Install the package.
Restart ComfyUI after installation if required.
2. Patch SageAttention Correctly
After loading your model and LoRAs, you must add the node:
Patch Sage Attention KJ
Then select one of the following modes:
sageattn_qk_int8_pv_fp16_triton
sageattn_qk_int8_pv_fp16_cuda
Important Notes
The patch node should be applied after loading the checkpoint/model and LoRAs.
Using the wrong SageAttention backend may result in completely black outputs.
If one backend does not work on your system, try the other option.
Recommended Order
Load Checkpoint
    ↓
Load LoRA(s)
    ↓
Patch Sage Attention KJ
    ↓
Sampler / Generation Nodes
This issue is commonly related to unsupported or unstable SageAttention kernel configurations on certain GPU, CUDA, or PyTorch combinations.
Useful Links
Github Issue