flux_1_kontext_dev_grouped example workflow doesn't work

### Custom Node Testing

- [x] I have tried disabling custom nodes and the issue persists (see [how to disable custom nodes](https://docs.comfy.org/troubleshooting/custom-node-issues#step-1%3A-test-with-all-custom-nodes-disabled) if you need help)

### Expected Behavior

really call the model and modify image

### Actual Behavior

After updating to the latest version v0.3.51, the example workflow is no longer valid. It only generates a merged preview image in less than a second, but does not call the model.

### Steps to Reproduce

just flow the exmaple tutorial flux_1_kontext_dev_grouped in https://docs.comfy.org/zh-CN/tutorials/flux/flux-1-kontext-dev

### Debug Logs

```powershell
got prompt
Failed to validate prompt for output 144:
* KSampler 175:3:
- Required input is missing: latent_image
Output will be ignored
Failed to validate prompt for output 178:5:
* KSampler 178:3:
- Required input is missing: latent_image
Output will be ignored
Failed to validate prompt for output 175:5:
Output will be ignored
Prompt executed in 0.01 seconds
```

### Other

_No response_