Apple Silicon (M2 Ultra): Official HunyuanVideo 1.5 Image2Video produces black video above 73 frames

[marckaufung-cmyk]

Hello everyone,

I have encountered what appears to be a fully reproducible issue using the official HunyuanVideo 1.5 Image2Video workflow on Apple Silicon.

System

• Mac Studio M2 Ultra
• 64 GB Unified Memory
• Latest macOS
• Fresh installation of ComfyUI Desktop (installed approximately 5 days ago)
• Official Comfy-Org HunyuanVideo 1.5 workflow
• Official Comfy-Org repackaged models
• Official HunyuanVideo VAE

Workflow

No modifications except changing the frame count.

Resolution:
832 × 480

Decoder:
Normal VAEDecode (not tiled)

Inference steps:
20 (default)

Results

73 frames:
✅ Works perfectly.

81 frames:
⚫ Video generation completes successfully, an MP4 file is written, but every frame is completely black.

89 frames:
⚫ Same result.

97 frames:
⚫ Same result.

121 frames:
❌ MPSGraph reports an INT_MAX tensor dimension error.

I also experienced one MPS out-of-memory error during earlier testing, but after restarting ComfyUI that disappeared. The black video issue remained fully reproducible.

The workflow finishes successfully and writes an MP4 file without reporting any decoder error.

Has anyone seen this on Apple Silicon?

Is anyone able to reproduce this on M1/M2/M3/M4 hardware?

I can provide the workflow JSON if needed.
Wan2.1_I2V_720p_14B_M2Ultra_Euler.json